Note: Italicized paragraphs describe scenes added for the film's 1997 special edition and updated for its DVD release.
An opening title card reads:
'A long time ago in a galaxy far, far away...
'It is a period of civil war. Rebel spaceships, striking from a hidden base, have won their first victory against the evil Galactic Empire. During the battle, Rebel spies managed to steal secret plans to the Empire's ultimate weapon, the DeathStar, an armored space station with enough power to destroy an entire planet. Pursued by the Empire's sinister agents, Princess Leia (Carrie Fisher) races home aboard her starship, custodian of the stolen plans that can save her people and restore freedom to the galaxy.'
Following the opening crawl, the frame moves down in the star field and we see a pitched battle between two starships in orbit around the desert planet of Tatooine. A small Rebel blockade runner, the Tantive IV, is being pursued by a mammoth Imperial star destroyer, the Devastator. Inside, protocol droid C-3PO (Anthony Daniels) and utility droid R2-D2 (Kenny Baker) are tossed about as their ship endures a barrage of laser bolts, and "3PO" concludes that escaping capture will be impossible. The Rebel ship is so heavily damaged that its main power reactor must be shut down. It is caught in the Imperial destroyer's tractor beam, pulled into the hold of the larger ship, and boarded by stormtroopers from the Empire's 501st Legion.
A huge firefight ensues in the corridors of the Rebel ship, with many Rebel soldiers being lost in the battle. When the smoke clears, Darth Vader (David Prowse; voice: James Earl Jones), a man dressed in a black cape, black armor, and a black helmet that obscures all his features, briefly surveys the damage before interrogating the ship's captain, Antillies, who claims that the ship is on a diplomatic mission to the planet Alderaan. Vader perceives that he is lying, noting that a consular ship would have an ambassador on board. (In actuality there is a diplomat aboard - Princess Leia Organa - but she is hiding from Vader, the second-ranking man in the Empire, which tends to support Vader's thesis that somebody on this ship is up to something.) Upon learning that "the plans" were not downloaded into the ship's computer, Vader strangles the captain. He then tells the troops to search the entire ship and to bring all the passengers to him - alive.
C-3PO and R2-D2 manage to escape damage from the firefight. R2-D2 meets up with Princess Leia, who loads him with the stolen plans and records a holographic message for the small droid to take to the planet's surface. R2-D2 and C-3PO get away from the ship aboard an escape pod and go to the planet below; Imperial troops choose not to destroy the pod, as their scans detect no living organism on board, and presume it ejected due to a malfunction. Moments later the princess is stunned by Imperial troops and taken to Vader. He tells her that the Rebels have stolen some secret Imperial plans and transmitted them to her ship. She feigns ignorance and protests to Vader that she is a member of the Imperial Senate on a diplomatic mission to the planet Alderaan, but Vader doesn't believe her and orders her taken away. Vader's adjutant aide, Commander Jir (Al Lampert), insists that holding her captive is dangerous; news of her captivity would generate sympathy for the rebellion against the Empire. Vader instructs Jir to deceive the Senate and permanently erase any trace of Leia's whereabouts by faking her [accidental] death. Upon being notified by another officer that an empty escape pod was jettisoned during the firefight, he concludes that the Princess hid the stolen plans in the pod.
C-3PO and R2-D2 land on the desert planet; R2-D2 mentions a mission to deliver some plans, but C-3PO is more concerned with staying in one piece long enough to find civilization. The two split up, and both are eventually captured by a group of diminutive scavengers called Jawas. The Jawas are junk traders, and R2-D2 and C-3PO are their newest assets. Meanwhile, a unit of Imperial Sandtroopers find the crashed pod and discover droid parts and tracks leading away from the crash site.
The Jawas travel to the Great Chott Salt Flat settlement to sell droids and equipment to local homesteaders, eventually arriving at the homestead of Owen Lars (Phil Brown), a moisture farmer. The farmer purchases C-3PO for his translation skills, as he is fluent in six million forms of communication, but initially decides to buy a cheaper utility droid, R5-D4, which breaks down almost immediately after purchase. Eager to deflect accusations of selling shoddy merchandise, the Jawas offer R2 as a replacement. Owen accepts and tells his young 18-year-old nephew, Luke Skywalker (Mark Hamill), to clean them up and put them to work. Luke had plans to meet some friends in the nearby town of Anchorhead, but his plans are put aside for work. During the cleanup, Luke stumbles across a short clip of the message stored in R2 by Princess Leia. The message is for someone named 'Obi-Wan Kenobi', and is a desperate plea for help. R2 insists that the message is simply a malfunction ("old data"), but Luke insists on hearing the complete message, intrigued by Leia's beauty. R2 then states that if Luke removes his restraining bolt, he might be able to play the rest of the message. Luke removes the bolt, but R2 doesn't play the message and claims not to know what Luke is talking about. Luke is called away for dinner (forgetting to replace the bolt, which will keep R2 within the boundaries of the moisture farm) and asks C-3PO to finish cleaning R2.
During dinner, Luke tells his aunt and uncle that the droids may belong to someone called Obi-Wan Kenobi. This news greatly disturbs Uncle Owen, but he won't say why. Luke asks if Obi-Wan is possibly related to a hermit named Ben Kenobi who lives several miles away in the Dune Sea area, a vast terrain of sand and rocky canyons. Owen claims that Ben is "just a crazy old man," and that Obi-Wan is dead; Owen makes a comment which seems to indicate that Obi-Wan Kenobi knew Luke's long-deceased father, Anakin, but when Luke presses Owen for details, his uncle quickly changes the subject and instructs Luke to erase the droids' memories the next morning. Luke - who hopes to leave home for training at a nearby Imperial Military Academy to become a space pilot - leaves the room angrily to return to cleaning the droids. Luke's Aunt Beru (Shelagh Fraser) tells Owen that Luke is too much like his father to remain with them, but Owen holds out hope that Luke's desire for adventure will subside - and expresses a fear that Luke is too much like his father... suggesting that Owen may know something of Anakin's terrible past.
After dinner, Luke discovers that R2-D2 has escaped to find Obi-Wan Kenobi. Luke tells 3PO that it's too late to look for R2 because of the dangerous Sand People (also called Tusken Raiders) in the area, and that they will set out first thing in the morning to go look for him (hopefully before Owen discovers that due to Luke's negligence, his newest investment has disappeared).
The following morning, Luke and 3PO set out in Luke's landspeeder to find R2. They locate him on the scanner and catch up with him. As soon as they find him, R2 informs them that his own scanner is picking up several creatures closing in on them. Luke fears the Sand People have found them, and confirms it using a set of minoculars. One ambushes them, hitting Luke over the head and knocking him unconscious. C-3PO goes tumbling down the side of a sand dune. R2 runs and hides.
After stealing some parts off of Luke's speeder, the Sand People are frightened away by the sound of a vicious beast. The sound comes from a mysterious hooded figure. The figure checks on Luke and takes his hood off to reveal his features. He is an old, bearded man, who gently touches Luke's forehead. Luke quickly comes to and recognizes the man as Ben Kenobi (Alec Guinness). Luke tells the man that his droid claims to belong to an Obi-Wan Kenobi. This knowledge startles the old man, who reveals (with a look of ancient mystery on his face) that he is Obi-Wan Kenobi but that he hasn't gone by that name in many years. After rescuing C-3PO, they go to Obi-Wan's home to discuss the matter.
At Obi-Wan's home, Luke learns that Obi-Wan knew Anakin and that they were both Jedi Knights of the Old Republic and veterans of the talked about 'Clones Wars'. Luke had been told by his uncle that his father was a navigator on a spice freighter; Owen had been trying to protect Luke from the truth about his father, or perhaps simply trying to keep him safe. (Note: it's not clear that Owen knows the truth about Luke's father, other than that he was killed in a dangerous line of duty). Obi-Wan then produces Anakin's lightsaber, an energy sword which was the chosen weapon of the Jedi Knights; he seems to have kept it safe for some time. He gives the weapon to Luke, saying that Anakin wanted him to have it when he was old enough, but Owen would have none of it. Obi-Wan explains that a Jedi receives his power from the Force, an energy field that is created by all living beings that "surrounds us, penetrates us, and binds the galaxy together." But there is also a Dark Side to the Force, which draws power from negative emotions and baser impulses. A young Jedi named Darth Vader, who was once a pupil of Obi-Wan, was seduced by this Dark Side. Vader betrayed and murdered Anakin, then became the Dark Lord of the Sith, the most feared enforcer of the Emperor. In this capacity, he proceeded to hunt down his former comrades, and the Jedi Order is now all but extinct.
At this point Obi-Wan has R2 play Princess Leia's complete message. The princess reminds Obi-Wan of his past service to her father in the Clone Wars, and conveys his plea to assist in the Rebellion against the Empire. She senses that her mission to bring Obi-Wan to Alderaan has failed, and tells Obi-Wan that she has embedded information crucial to the rebellion in R2's memory banks. She asks Obi-Wan to deliver the droid to her father on Alderaan so that the information can be retrieved, and repeats her plea that he is now her "only hope."
Obi-Wan cannot hope to undertake such a mission alone due to his advanced age, so he tells Luke that he should learn the ways of the Force and accompany him to Alderaan. Luke is adamant that he can't go, and that he must stay on Tatooine and help his uncle. Obi-Wan counters that the Rebellion needs Luke's help, and that the young woman in the message needs Luke's help (though she has not mentioned any personal request for help). They decide to go to the city of Anchorhead so that Obi-Wan can book a transport to Mos Eisely space port.
Meanwhile, the Devastator has docked at the Death Star, a gargantuan space station resembling a small moon. Vader rendezvous with Grand Moff Wilhuff Tarkin (Peter Cushing), the high ranking governor of the Imperial Outland Regions, and they enter a conference room where they meet the station's Command Triumvirate leaders in a high level conference: Admiral Antonio Motti (Richard LeParmentier), High General Cassio Tagge (Don Henderson), and Chief Officer Mordramin Bast (Leslie Schofield) among other Imperial officers. As the Triumvirs argue about the best way to exploit their newest "technological terror," Tarkin tells them that the Emperor has decided to dissolve the Imperial Senate; giving full control of the Galaxy's star systems to each of the regional governors under him and use the Death Star to intimidate all of the Empire's star systems into submission, suggesting that fear of force is preferable to its actual use. Admiral Motti is extremely confident in the new space station, calling it 'the ultimate power in the universe.' However, General Tagge is adamant that the Death Star is not invincible, and that the Rebels will figure this out if they have a chance to read its schematics. Vader tells them that the ability to destroy a planet is insignificant next to the power of the Force. Motti callously mocks Vader's Jedi heritage, noting that the Force has not helped him recover the stolen schematics or pinpoint the Rebellion's headquarters. Angered, Vader uses the Force to strangle Motti, until Tarkin orders him to stand down. The commanders decide to focus on interrogating Leia until she gives up the location of the Rebel Headquarters. They will then use the Death Star to destroy it, killing two birds with one stone.
As Luke and his companions travel to Anchorhead, they find the Jawa sandcrawler, completely destroyed with all the Jawas slaughtered; although they appear to be victims of the Sand People, Obi-Wan recognizes signs which indicate an attack by Imperial stormtroopers. Luke realizes that the only reason Imperial troops would kill Jawas is because they are looking for the droids which escaped the battle, and he races home, over Obi-Wan's objections that he is likely endangering his own life, hoping to warn Owen and Beru.
However, Luke is too late. The Imperials have apparently come and gone, burned the homestead, and killed his aunt and uncle. Luke returns to Obi-Wan (who has used the opportunity afforded by Luke's trip to accord the massacred Jawas some measure of dignity), saying that with no reason to remain, he wants to go with him to Alderaan. More importantly, he declares his wish to learn the ways of the Force and become a Jedi like his father once was.
Luke, Obi-Wan and the two droids now travel to Mos Eisley, the spaceport and capital city of Tatooine. Before entering the city, Obi-Wan warns Luke and the droids that Mos Eisley is a hotbed of crime and near-lawlessness. Luke assures Obi-Wan that he knows how to handle himself in a fight. Upon entering the spaceport they are approached by Imperial troops at a roadblock asking questions about the two droids they have with them. Obi-Wan appears to induce a trance-like state in the lead guard, persuading him that these are not the droids they are looking for. When Luke is puzzled by the ease of their passage, Obi-Wan explains that the Force can have a strong influence on the weak-minded.
At the Mos Eisley Cantina, Luke gets into a scuffle with two criminals, a deformed human named Dr. Evazan and his alien companion Ponda Baba, who threaten to kill him. When one of the creatures pulls a gun on Kenobi, the old Jedi Knight defends himself with his lightsaber - slashing off the creature's gun arm before it can shoot. Moments later they meet smuggler Han Solo (Harrison Ford), captain of the Millennium Falcon, and his first mate, Chewbacca (Peter Mayhew), a 7-foot-tall, 200-year-old Wookiee. Upon learning that Obi-Wan and Luke are trying to avoid Imperial capture, Captain Solo gives his price as 10,000 credits for the trip. Luke balks at that price, stating that they could almost buy their own ship for that, but Han is dubious that they could fly it themselves. Obi-Wan tells Solo that they will pay him 2,000 credits now and 15,000 more once they reach Alderaan. Han agrees.
After Luke and Obi-Wan leave, Han tells Chewbacca that 17,000 credits could really save his neck. As Chewbacca leaves to make pre-flight preparations, Han hangs back to take care of their bar tab, and is stopped by Greedo (Maria De Aragon and Paul Blake), a bounty hunter working for feared crimelord Jabba Desilijic Tiure, aka: Jabba the Hutt. Apparently some time earlier, Jabba had hired Han to transport a shipment of glitterstim spice (an illegal narcotic), but Han had to dump the shipment due to an unexpected Imperial boarding. As Greedo points a blaster pistol at Solo and forces him toward a secluded section of the bar, Han insists that he has the 8,000 credits he needs to cover the loss. Greedo suggests that Solo give it to him as a bribe not to turn him over to Jabba, forcing Han to admit that he doesn't actually have the money yet. Realizing that Greedo will either turn him over to Jabba or kill him for the bounty that Jabba has placed on him, Solo quietly removes his heavy pistol under the table, and when Greedo admits that he would just as soon see him dead as alive, Solo pre-emptively fires and kills him. On his way out, Han throws the bartender a few coins, apologizing for "the mess" he left.
At the docking bay, Han is confronted by Jabba the Hutt and several other associates. Jabba expresses frustration over Greedo's death, and reminds Han of the nature of their business; he cannot "make any exceptions" of those who fail or cross him, lest he appear weak. Han insists that he will soon have enough money to pay off his debt, with interest, he just needs more time. Jabba reluctantly agrees, but warns Han that this is his last chance.
Luke sells his landspeeder to raise money for their initial payment to Captain Solo. They head to the docking bay where the Millennium Falcon is being prepared for flight. Luke is somewhat perturbed to discover that the Falcon is a 60-year-old, run-down YT-1300 freighter, but Han assures him that he has made extensive modifications to ensure that she can run rings around any modern capital ship. Meanwhile, Imperial troops believe they are hot on the trail of the two droids when a local informant tells them the whereabouts of the fugitives after recognizing Luke and Obi-Wan.
No sooner do Luke, Obi-Wan and the droids board the Millennium Falcon than the Imperial troops come running into the docking bay, hoping to arrest Luke and Obi-Wan and capture the droids. The troops fire at Solo and the Falcon, but the ship manages to escape. Once they clear the planet, they are immediately pursued by two huge Imperial star destroyers. Solo remarks that his passengers must be of particular interest to the Empire. They jump to light speed, escaping the Imperial ships.
Princess Leia has been tortured by the Imperials and undergone a mind probe in an effort to extract the location of the Rebels' home base. They have found nothing. Tarkin, Vader, and Motti shift tactics, threatening to destroy the Princess's home planet of Alderaan if she won't reveal the Rebels' location. She reluctantly tells them that the Rebel base is on the planet Dantooine. Tarkin then orders his officers to proceed with Alderaan's destruction, noting that Dantooine is too remote to make an effective demonstration of the Death Star's power. Alderaan is destroyed by a single blast from the Death Star's enormously powerful laser blaster while Leia is forced to watch.
On board the Millennium Falcon, Obi-Wan is training Luke in the ways of the Force when he is greatly disturbed by a tremor in the Force. He feels that millions of people have died in an instant amidst great suffering, though he doesn't know how. He decides to meditate on this further as Luke continues an exercise in allowing the Force to guide his reflexes. Han is not impressed, and explains that he does not believe in the Force. Luke, however, manages to use his lightsaber to deflect four laser bolts in a row from a remote droid - all while wearing a helmet which covers his eyes.
Back on the Death Star, Tarkin and Vader receive a report that there once was indeed a Rebel base on Dantooine but it has long since been abandoned. Outraged at Leia's successful trickery, Tarkin orders her scheduled for execution.
Luke realizes that he is learning how to sense the Force. One of the Falcon's signals informs them that they are approaching Alderaan, but upon exiting light speed, they find the Millennium Falcon is in an asteroid field instead of Alderaan's orbit. Han confirms that they are in the right location but that the planet is missing; Obi-Wan quietly states that the planet has been destroyed by the Empire, but Solo laughingly insists that all the Empire's ships combined wouldn't have enough firepower to destroy a planet. Moments later they are overflown by an Imperial Twin Ion Engine (TIE) snubfighter. Obi-Wan concludes it is too small for long range flight, so there must be an Imperial base or ship nearby. As they chase after the fighter to keep it from notifying the Empire of their location, they see the fighter heading toward a small moon - the Death Star. They are caught in the Death Star's tractor beam and, helpless to resist, are pulled aboard the station into a docking bay. Obi-Wan tells them that neither fighting or surrender are viable choices, but a third option is available to them.
Imperial troops board the Falcon, but its crew are hiding in smuggling compartments below the floor. Vader orders scanning equipment to be brought aboard to look for life signs. While standing near the Falcon, he senses a presence he has not felt for some time. Vader leaves the hangar, pursued by the frustrating sense he is overlooking something of great importance.
When a scanning teams boards the Falcon to set up their equipment, Luke and Solo manages to overpower them and lures the two guarding stormtroopers just outside on board as well to kill them both and steal their armor uniforms. The helmets conceal their identity and allow them to infiltrate a troop command center outside the docking port. Inside the command center, R2 plugs into the station computer system and discovers the location of the tractor beam generator. Obi-Wan sets out to shut down the generator so that the ship can leave. Luke wants to accompany him, but Obi-Wan orders Luke to stay, noting that Luke's destiny now splits paths from his own. Perhaps sensing that this is the last time he will see Luke in this reality, he tells Luke, "The Force will be with you... always."
After Obi-Wan leaves, R2 discovers that the princess is being held prisoner on board the station. Luke suddenly takes the initiative, sparing no effort to convince Solo and Chewbacca to assist him in what is surely going to be a very risky rescue. Han, initially scared for his own neck, eventually agrees, but only after Luke suggests that a great monetary reward would surely follow her rescue. Luke and Han take Chewbacca "captive" and assume their trooper identities in order to infiltrate the prison block. In the prison block, the officer in command becomes suspicious of their arrival since he was not notified about any prisoner transfer. As a result, Luke and Han's escorted "prisoner" escapes and a firefight erupts between the Imperials and Luke, Han, and Chewbacca. They manage to take out all the Imperials, but set off an alarm in the process. A squad of troops are sent to investigate. Han and Luke know they have only moments to find the princess's cell and escape.
They find the princess, but the arriving troops cut off the only escape route. Leia shoots a hole in a garbage chute and tells everyone to dive in. They escape the Imperials, only to find themselves trapped in a large garbage compactor. To make matters worse, the compactor also houses a large, serpent-like creature - the dianoga - which yanks Luke under the murky, stagnant water in the compactor, almost drowning him. The creature inexplicably lets Luke go, but just as they catch their breath, the compactor activates and the walls begin to move in, threatening to crush Han, Luke, Leia, and Chewbacca. Luke calls 3PO on the communicator and orders him to have R2 shut down all garbage compactors in the detention level. R2 complies just in time to save them and then open their compactor's door to let them out.
Meanwhile, Vader informs Tarkin that he senses through the Force that Kenobi is aboard the station. Tarkin is doubtful, but the discussion is soon interrupted by an emergency report: Princess Leia has escaped! Vader tells a shocked and bewildered Tarkin the true explanation for Leia's impossible escape - "Obi-Wan is here. The Force is with him." Sensing that Obi-Wan wishes a final showdown, Vader sets off to find him. Unbeknownst to anyone, Kenobi has deactivated the tractor beam generator.
After their escape from the compactor, Luke and Han dispose of their stormtrooper armor, but keep the troopers' utility belts and weapons. On their way back to the ship they're cut off by more troops. They are split up, with Han and Chewbacca fighting together and Luke and Leia running on their own.
After being cornered between a great air shaft and a group of troopers, Luke shoots a blast door's controls with his blaster, locking the troops on the other side of the door. Unfortunately, the blast also destroys the controls that extend the bridge across the air shaft. After a gunfight with stormtroopers on the other side of the shaft, Luke uses a cable and grappling hook from his freshly confiscated Imperial utility belt to swing himself and Leia safely across the gorge.
Obi-Wan, on his way back to the Falcon, encounters Vader. They exchange barbed comments. Vader boasts to his former master that he is so much more experienced and powerful than he was the last time they met that the tables have now turned, with Vader the more powerful of the two. Obi-Wan replies that Vader's turn to evil has made him oblivious to the Force's true power. A ferocious lightsaber duel ensues.
Luke, Leia, Han and Chewbacca meet at the entrance to the docking bay. The lightsaber duel on the other side of the bay distracts the troops guarding the ship, allowing the four of them, along with R2 and 3PO, to sneak across to board the Falcon. As Kenobi and Vader continue to fight, Kenobi informs Vader that if Vader strikes him down, he shall become even more powerful, beyond what Vader could possibly imagine. Kenobi, seeing that the four heroes and two droids are safely boarding the Falcon, takes one last look from his comrade's son to the man who betrayed him, and smilingly withdraws his saber, allowing Vader to slice through him. His body instantly disappears. Vader is stunned and confused by this, as he determines that no one is in Kenobi's now-empty cloak on the floor.
Luke, appalled by the sight of his mentor being struck down by Vader, lets out a shout of horror, alerting all of the troops to their presence. Another firefight immediately erupts, and they barely make it aboard the ship with their lives. Luke stays behind, attempting to shoot every Imperial soldier in the hangar, despite his friends urging him to join them on the ship so they can escape. Finally, he relents, hearing Obi-Wan's voice telling him to run, as Vader catches a glimpse of him through a rapidly closing set of blast doors. When the Falcon flies out of the docking bay, the Imperials are unable to activate the tractor beam, thanks to Kenobi.
Having blasted their way out of the station's defense range, they are confronted by four Imperial TIE fighters. Luke and Han man two large gun turrets on the top and bottom of the Falcon and manage to destroy all four ships. Han starts to boast to Leia about his amazing abilities during her rescue. She insists that the Empire let them escape in order to track them to the Rebel base. Han is doubtful of that as she explains to Han that R2 is carrying the technical readouts to the Death Star. She has high hopes that when the data is analyzed, a weakness can be found in the station.
Back aboard the station, Leia's fears are confirmed as Vader and Tarkin discuss their plan to track the Falcon to the hidden Rebel base. The Falcon makes it to the base, located on the fourth moon of the gas giant Yavin Prime. After R2's data is analyzed, it is determined that the Death Star does indeed have a weakness that can be exploited; a small (two meters) exhaust port not protected by any shielding, through which a well-placed proton torpedo could reach the main reactor and destroy the station. The port is situated in a narrow trench protected by General ARea Defense Integration Anti-spacecraft Network (GARDIAN) turbo-lasers. The Rebel commander, General Dodonna (Alex McCrindle), theorizes that since the GARDIAN array is designed to repel large scale assaults from capital ships, it could easily be outmaneuvered by smaller and faster snubfighters. A plan is devised in which a squadron of Y-Wing assault bombers (Gold Squadron, led by Captain Jon "Dutch" Vander (Angus MacInnes)), will skim the trench. A second squadron (Red Squadron, commanded by Captain Garven Dreis (Drewe Henley)), comprised of the faster, more maneuverable X-Wing snubfighters, will attempt to draw enemy fire away from the bombers. Luke will be flying one of the X-Wings, under the call sign Red Five. Fellow pilot Wedge Antilles (Denis Lawson) is skeptical about succeeding, but Luke is confident that the task can be accomplished, noting that he used to shoot at animal targets on Tatooine which were not much bigger than two meters.
The Rebels set out to attack the Death Star just as the station enters the Yavin system. The Death Star will have to orbit to Yavin's far side in order to have a shot at the moon on which the base is located. The approximately 30 Rebel fighters have less than 30 minutes to fly to the station and destroy it.
As Luke heads to the hanger, he is reunited with Biggs Darklighter (Garrick Hagon), who used to fly with Luke on Tatooine. Biggs congratulates Luke on finally making it off Tatooine and tells him that the coming battle will be just like old times.
Having apparently collected the balance of his 17,000 credits payment for delivering the plans to the Rebellion (plus some unspecified reward for helping Leia escape from the Death Star), Han refuses to join the fight, stating that his reward will be useless if he is killed, and that he would rather take his money and go pay off his debts. Luke is disappointed, but boards his fighter and takes off, right after R2 is loaded into the rear of the fighter to provide technical assistance. Upon departure, he hears what sounds like Obi-Wan's voice speaking to him, saying "The Force will be with you." He quickly dismisses it.
Both squadrons approach the Death Star and Wedge Antilles briefly marvels at its size before Captain Dreis cuts off the idle chatter and orders the squadrons to attack speed. Red Squadron initiates a strafing run on the station's surface to divert attention from the bombers, and Luke makes a run that detonates a mammoth fire within part of the Death Star - a fire so large his own ship suffers minor burns. When Vader is informed that the GARDIAN turbo-lasers are having trouble targeting the small rebel ships, he orders fighters led by Black Squadron, his personal elite TIE fighter squadron, to engage the X-Wings individually. In short order, six TIE fighters join the battle, soon followed by others, and Red Squadron scrambles to keep them away from the trenches. Dreis warns a wingman of an attacking TIE fighter but the X-Wing is immediately shot down before Biggs himself comes under attack; Luke swings behind the attacker and shoots him down.
Vader notices Dutch and his Y-Wing group breaking away from the primary attack. He assigns two Black Squadron pilots, Mauler and Backstabber, to escort him as he boards a TIE Advanced x1 fighter to engage the bombers himself. Before this command group launches, the sky battle rages on and Luke himself comes under attack; Wedge rescues him by shooting into the belligerent TIE fighter literally nose to nose, just as Dutch and Gold Squadron commence the attack into the trenches.
Vader and his two wingmen easily outmaneuver the Y-Wings, methodically dispatching them one by one; first pilot Tyree is killed, as Dutch begins to panic despite angry urging by his surviving wingman. Dutch is then killed and the surviving Gold Squadron ship aborts his run before he himself is destroyed.
With Gold Squadron effectively wiped out, Dreis orders the surviving X-Wing pilots to start a second attack run down the trench. As they approach the exhaust port, Dreis turns on his targeting computer as two other ships cover his tail from enemy fire. The escorting ships are destroyed, but they buy enough time for Dreis to take a shot at the exhaust port. His shot misses and merely impacts on the surface. Moments later he loses an engine to Vader's gunnery and his fighter spirals into the surface of the station.
Now nominally in charge of Red Squadron, Luke decides that it is his responsibility to try to destroy the port. R2 is preoccupied trying to keep the ship running, despite all of the damage they are sustaining. With Biggs and Wedge flying his wing, they start down the trench. Moments later, they are pursued by Vader and his wingmen, who partially disable Wedge's ship. Luke tells Wedge to disengage, seeing that he can't be of any help in a crippled ship. Vader allows Wedge to withdraw, ordering his men to continue to pursue the two ships in the trench. Vader fires again, hitting Biggs' ship and destroying it. Luke is grieved by the loss of his friend, but presses on.
As Luke gets closer to his target, he hears the voice of Obi-Wan, telling him to "use the Force" and rely on his instincts more than the technology in his ship. Heeding that advice, Luke switches off his targeting computer and continues flying down the trench. When asked by Mission Control why he switched off the computer, Luke responds that nothing is wrong.
Meanwhile, the Death Star has completed its run around Yavin and is cleared to fire on the Rebel moon. The countdown for the firing sequence begins. Bast tells Tarkin that he has analyzed the attack and concludes there is a real threat to the station. Tarkin scoffs at evacuation and insists the Empire will prevail. He remains on the station while some of the Imperial officers and troops evacuate as a precaution.
As Luke draws on the power of the Force to help him hit his target, Vader senses the strength of the Force in his prey. He takes a shot, which misses the ship but hits R2-D2. Just as he locks on to Luke's ship to finish him off, Backstabber's ship explodes unexpectedly. Out of nowhere appears the Millennium Falcon, which has just destroyed the Imperial fighter - diving vertically towards Vader and the remaining wingman. This sudden turn of events distracts Mauler; he loses control of his ship and crashes into Vader's. Mauler's ship ricochets into the trench wall, destroying it, and sends Vader's ship spinning out of control, up and away from the Death Star.
Han informs Luke that he is all clear to fire. Luke, having drawn upon the power of the Force, releases his proton torpedoes, which enter the exhaust port perfectly on target. Luke, the Falcon and a few other fighters race away from the Death Star just as the Death Star prepares to fire on the moon. Only seconds before the station fires, it explodes into a huge fireball, sending millions of fragments into space. Tarkin, Motti, Tagge, and most of the senior Imperial staff are killed. With that triumph, Kenobi reminds Luke that the Force will be with him, always.
Vader, having been thrown into space during his collision with the wingman, is now apparently the only one to have escaped the station's destruction. He eventually manages to regain control of his wildly gyrating fighter, and when he finally stabilizes, he flies off to meet the Imperial Fleet as the Rebels head home to their base. When they reach the base, Luke is clearly delighted that Han returned to help him. Leia is thrilled to see both of her friends alive. And everyone is ecstatic that the Death Star has been destroyed. Their celebration is briefly interrupted as R2 is pulled from Luke's ship. He is heavily damaged from Vader's gunfire and does not respond to C-3PO. The golden robot is terribly concerned, but Luke and two mechanics assure him that R2 is repairable and will be fine.
Later, an awards ceremony is held in a huge hall. Hundreds of Rebel soldiers, officers, and pilots are present. A door at the rear of the hall opens to reveal Luke, Han, and Chewbacca. They walk down the aisle to where Leia awaits, along with several Rebel leaders and dignitaries.
Also present are a freshly polished C-3PO and a freshly overhauled and looking better-than-new R2-D2. Upon reaching the front of the great hall, Luke and Han are awarded medals for bravery by a smiling Princess Leia. The hall erupts into thunderous applause.