Columbus, Ohio Year: 2045 A.D.
We open in a place called "The Stacks", as it is made up of a number of trailers structured on top of one another. Wade Watts (Tye Sheridan) is an orphan who lives with his aunt Alice (Susan Lynch) and her abusive boyfriend Rick (Ralph Ineson). Like the rest of this dystopian world, Wade escapes his reality by entering The OASIS (Ontologically Anthropocentric Sensory Immersive Simulation), a virtual reality world where people can enter as avatars to play video games, entertain themselves, and seek pleasures they can't find so easily in the real world. One can come across characters like Batman, Freddy Krueger, and even Hello Kitty. It becomes so intense due to the fact that whatever is earned in the OASIS can be taken away if the avatar dies. Wade's avatar is Parzival, and he frequently interacts with Aech (Lena Waithe), a huge muscular mechanic, as well as the samurai Daito (Win Morisaki) and fighter Sho (Philip Zhao), although he has never met either of them in person.
The OASIS was created by James Halliday (Mark Rylance) and Ogden Morrow (Simon Pegg), who both founded Gregarious Games before developing the OASIS. Halliday passed away five years earlier, but not before leaving fans with the ultimate challenge. In his final video, Halliday informed everyone that he has hidden an Easter egg deep within the game that will be unlocked after three challenges have been completed. The one who finds the egg will inherit Halliday's stock in Gregarious Games, which is roughly half a trillion dollars, and total control over the OASIS. The winners will be greeted by Halliday's avatar, Anorak, an all-knowing wizard.
Wade explains that people have been trying for years to find the egg (they're called "egg hunters", or "Gunters"), but to no avail. A company called IOI (Innovative Online Industries) has rounded up a number of players with debts to pay called Sixers to head in and find the egg in their Loyalty Centers to pay off debts. The first challenge was unlocked long ago, which is a race into Central Park. Wade enters as Parzival and uses the DeLorean as his car. The Sixers all arrive as a team. The race begins, and Aech mows down a lot of Sixers. Wade races ahead of the pack until the track is attacked by King Kong. Wade almost makes it to the finish line until he realizes nobody can make it across without Kong destroying them. He spots well-known player Art3mis (Olivia Cooke) about to make it across, but he stops her, just as Kong catches her motorcycle and destroys it.
Aech invites Wade and Art3mis to his garage so that he can fix the motorcycle. He is currently building an Iron Giant. Aech is also able to detect that Wade likes Art3mis due to her reputation in the game, as well as her avatar being attractive. After Aech fixes the motorcycle, Art3mis leaves, and Wade must leave when he hears his aunt calling.
Wade returns to his home where Rick tries to attack him over a matter in the game since Wade took Alice's gloves for the game. Rick had also apparently spent much of their personal money in the game. Alice threatens to kick Wade out if he touches her stuff again.
At IOI, CEO Nolan Sorrento (Ben Mendelsohn) is planning to create some kind of bug in the game that would spam the players' lenses with pop-ups and force them to pay to remove them. Sorrento is also desperate to find the egg and secure the massive fortune.
Back in the OASIS, Wade visits the Halliday Journals, which is a recollection of Halliday's memories. Wade speaks to the robot host, the Curator, who guides Wade to a much-viewed memory. It is after a launch party where Halliday and Morrow are discussing their futures in the industry, with Morrow choosing to leave Gregarious Games. Wade listens to a quote from Halliday about "going backwards", which Wade realizes is a clue to beating the first challenge.
Wade returns to the race, but as everyone goes ahead, he moves backwards and rides through an underground tunnel that allows him to completely avoid Kong. He is able to cross the finish line and make it to Central Park where he is greeted by Anorak, who presents him with the Copper Key, as well as a clue to the next challenge. Parzival becomes the highest-scoring player in the game, and it gets Sorrento's attention.
Sorrento enters the OASIS using his avatar. He meets with a bounty hunter called I-R0k (T.J. Miller) and hires him to find out who Parzival is. I-R0k presents Sorrento with a powerful item called the Orb of Osuvox.
Wade goes shopping in the OASIS and gets a few items, including a special suit that allows him to feel what goes on in the game. As Parzival, he becomes something of a celebrity. He helps Art3mis and Aech finish the race challenge, and they are followed by Daito and Sho. Their positions as the top five highest scorers give them the name "The High Five". The next clue involves "a creator who hates his own creation" and "a leap not taken".
Wade later joins Art3mis in returning to the Halliday Journals using a disguise to make him look like Clark Kent. They are taken by the Curator to revisit a memory of Halliday's where they learn that Sorrento started out as his intern. Halliday and Morrow are talking about a date that Halliday went on with someone named Kira, which is just her game handle, as her real name is Karen Underwood (Perdita Weeks), the woman who would later become Morrow's wife. Wade and Art3mis believe that she split Halliday and Morrow's partnership. Wade also notes that none of Halliday's other memories have any mention of Kira and even makes a bet with the Curator to prove it. After seeing that this is the only memory mentioning Kira or Karen Underwood, the Curator gives Wade a quarter as a reward. Art3mis then invites Wade to join her at a club.
Wade goes to the club called The Distracted Globe to meet with Art3mis. They dance together, and Wade finds himself falling for her. He suggests that they tell each other their real names, even though that's not recommended in the OASIS. After Wade tells Art3mis his name, he is overheard by I-R0k, who reports this information to Sorrento. Moments later, a team of Sixers break into the club to attack Wade and Art3mis. He uses a Zemeckis Cube to turn time back to a minute earlier, allowing them to escape. However, Art3mis is angry at Wade for nearly getting them in trouble, as her father died after being forced to work in a Loyalty Center under IOI.
Sorrento sends a message to Wade to offer him $50 million if he joins IOI and helps find the egg. As he is being projected into Sorrento's office in IOI, Wade notices the password to Sorrento's rig written on it. Wade outright refuses to join Sorrento, at which point he reveals he knows who Wade is and where he lives. Sorrento uses his assistant, F'Nale Zandor (Hannah John-Kamen) to send drones to The Stacks. Wade rushes to warn Alice and tries to call her, but Rick answers after stealing his suit and tells him not to call again. The drones then destroy the stack with Wade's trailer in it, killing Alice and Rick and sending the tower tumbling down. Wade runs to his OASIS trailer to warn his friends, but he is taken captive by a man with a face tattoo.
Wade wakes up and comes face-to-face with Samantha, who is the person behind Art3mis. She and a few others have gathered a small rebellion in an area not far from The Stacks and IOI. Wade and Samantha talk and almost kiss, until Samantha realizes this is what the clue to the next challenge is. The "leap not taken" refers to Halliday's regret of not kissing Kira when he had the chance on the one date they went on.
Wade and Samantha gather Aech, Daito, and Sho as they realize the next challenge is a movie, which is where Halliday took Kira on their date. They figure out that the movie they saw is "The Shining", in reference to "a creator who hates his own creation" since the late author Stephen King hated the movie version of his book. The Curator brings them to a virtual simulation of the Overlook Hotel. Since Aech has never seen "The Shining", he ends up encountering the twins, opening the elevator of blood, and running into the creepy woman in the bathtub before having to outrun Jack Torrance and his axe. Meanwhile, Samantha is able to find Kira dancing with zombies. She makes her way over to Kira, winning the challenge and being presented with the Jade Key. Thus, Art3mis becomes the highest scorer in OASIS, and Sorrento discovers Wade is alive when he sees that Parzival is now the second highest scorer. The Sixers themselves have less luck in getting through "The Shining".
F'Nale uses a drone to detect the tattoo face guy and find the rebellion's hideout. Samantha is taken while Wade gets out with the help of Aech, Daito, and Sho, whom he discovers are a woman named Helen, and brothers Toshiro and Shoto. They get away in Aech's van and head to rescue Samantha and stop Sorrento.
As the final challenge is in Castle Anorak on Planet Doom, Sorrento activates to Orb of Osuvok to create a force field around the castle to prevent other avatars from trying to get in. He has Samantha thrown into a Loyalty Center to work. Aech manages to hack into Sorrento's rig so that Wade and Daito can intimidate him and make him think they have made it into IOI by projecting the office into his view. Wade helps Samantha free herself from her chamber so that she can get out and make it to the War Room where Sixers are trying to beat the next challenge, which they figure is part of a collection of Atari games.
Wade sends a message to all OASIS players to tell them of what IOI is doing, and asks that they join him on Planet Doom to fight back. An army of thousands of avatars arrive to join the battle. Aech activates the Iron Giant to bring into the fight. Characters like Harley Quinn, a Halo team, and even the Ninja Turtles arrive as well. They attack the force field, and Sorrento uses Mecha-Godzilla to attack. Daito returns in the form of a Gundam mecha to fight. They even use Chucky the killer doll against the Sixers. The Iron Giant, the Gundam, and Art3mis all join forces to take down Sorrento and Mecha-Godzilla to allow Wade to proceed. He must sacrifice Art3mis in order for Samantha to be undetected by Sorrento.
Wade finds a Sixer who is playing "Adventure", which is the game that contains the final key. The Sixer comes closer to winning until he falls beneath the ice. Before Wade can make his attempt, Sorrento returns and fights him. As a last resort, Sorrento takes out a Cataclyst bomb to wipe out every avatar within range, including I-R0k and himself. However, the quarter that the Curator gave Wade turns out to be an extra life token, allowing Wade to stay inside the OASIS. Everyone is now watching him try to finish the challenge. Wade figures out that the player is not supposed to win the game, but find the Easter egg within "Adventure", and thereby unlocking the Crystal Key. Since he is still in Aech's van, and they are now being pursued by Sorrento and his goons, Wade struggles to use all the keys to unlock the vault, but he succeeds and finds the chamber with the Easter egg. He is greeted by Anorak, who presents Parzival with a contract to take over the OASIS, but Wade realizes this is a test reminiscent of when Halliday made Morrow sign over his shares of Gregarious Games, which Halliday regretted. The chamber them disappears to reveal the real Halliday in his own childhood room. He presents Wade with the red button that can shut the OASIS down for good if he chooses to. Wade almost hits it when Sorrento's van bumps into him. Halliday tells Wade that he ultimately realized that while escapism is fun, the real world is more important.
Aech drives the van to The Stacks where a group of people attempt to confront Sorrento. He finds their van, but the police arrive first. They have seen a video that Aech uploaded of Sorrento confessing to his crimes. He and F'Nale are then arrested. The team is then approached by Ogden Morrow, who calls himself "Og". He reveals to Wade that he was the Curator as well. With a team of lawyers, Og helps Wade secure control of the OASIS, but he wants to share control with his friends, which Og agrees with.
Wade's final narration states that with him and his friends in control of OASIS, they forced IOI to remove all their Loyalty Centers. They have also decided to shut down the OASIS on Tuesdays and Thursdays so that people may go out and enjoy the real world. We then see Wade and Samantha have moved in to a new apartment, a place he is finally happy to call home.