The Walt Disney Pictures logo and the movie title appear to the Norwegian song "Vuelie".
In a winter landscape, ice harvesters use saws and hooks to cut blocks of ice from a lake, chanting as they work about how ice is a powerful force that's both beautiful and dangerous ("Frozen Heart"). They load the ice blocks onto their sled and ride off. A young eight year old boy named Kristoff (Jonathan Groff) works alongside them (not very expertly), accompanied by his reindeer Sven (sounds: also Jonathan Groff). They try to imitate the ice harvesters with a single cubical block of ice and a small child's sled, and follow them away as the Northern Lights fill the night sky.
The camera follows the Northern Lights through the sky, before panning down on a stave castle, located on the shores of a Scandinavian fjord, ringed in by cliffs. That night, Princess Elsa of Arendelle (Eva Bella) is fast asleep when her five year old sister Princess Anna (Livvy Stubenrauch) tries to wake her up, wanting Elsa to play with her. Elsa playfully brushes Anna off, until Anna asks, "do you wanna build a snowman?" to which Elsa delightfully agrees.
Fully awake, the two sisters run downstairs to the ballroom. At Anna's urging, Elsa waves her hands, conjuring up a snow crystal, which she then shoots into the air. It explodes, raining snow down on them. To enhance the winter playground, she then stomps her foot, covering the entire floor with ice. They create a snowman that she nicknames Olaf, who likes warm hugs. The girls play gleefully with Olaf until Anna makes a leap Elsa wasn't prepared for and the blast of power meant to create a pile of snow hits Anna in the head, knocking her out and turning several strands of her hair white. Their parents, King Agdar and Queen Idun rush in, responding to Elsa's cries of anguish. They check on Anna and find her cold to the touch. Agdar and his wife hastily load both girls onto their horses and ride at full speed into the mountains.
As the royal family gallops through the forests at full speed, they pass by Kristoff, who is still being dragged on his sled by Sven. He becomes curious about the fact that one of the horses is leaving behind a trail of ice, in the middle of the summer.
Kristoff and Sven follow the ice trail to an empty clearing that appears to only be populated by a large assortment of moss-covered boulders. From the edge of the clearing, Kristoff watches as Agdar asks the motionless boulders to help him. Seconds later, all the boulders roll into a large circle around Agdar, Idun, Elsa, and the unconscious Anna. The rocks uncurl, revealing themselves to be trolls. The "boulder" Kristoff and Sven are watching the event from behind is another rock troll named Bulda, who immediately decides to adopt the visitors after Sven licks her.
Grand Pabbie (Ciarán Hinds), the leader of the trolls, shows up and asks Agdar if Elsa was born or cursed with her abilities. He observes that Anna is lucky she was hit in the head, as a hit to the heart would have been fatal. He advises the family that it might be best if Elsa doesn't use her powers around Anna. He alters Anna's memories so she has no knowledge of her sister's powers, remembering only the fun they've had (for instance, Anna will remember her indoor castle ice rink as a mundane winter day). Grand Pabbie warns Elsa that her powers will grow, and although they are beautiful, they will be a great risk to her if she cannot learn to control them, as fear will be her greatest enemy.
So Agdar and Idun take measures into their own hands based on what Grand Pabbie has told them. The palace is closed to most visitors. Staffing is reduced to a minimum. Anna and Elsa are separated, and having no memory of what has occurred, Anna is unable to comprehend why Elsa is not allowed to play with her. She often comes to Elsa's closed door and tries to coax her out by asking her if she wants to build a snowman ("Do You Want to Build a Snowman?"). As a further precaution, the sisters are also kept from leaving the castle.
While Anna's life is dull but normal, Elsa's powers grow stronger as she matures. Her father cautions her to wear gloves to keep her icy magic in check, and to conceal her feelings, because strong emotions seem to cause her powers to manifest in unexpected ways.
Ten years after the accident, the now teenaged princesses become orphans when their parents' ship capsizes in a storm, drowning them. After the burial, Anna goes again to Elsa's door, pleading for consolation from her only remaining family member. But Elsa, though she sits sadly on the the other side of the door, refuses to communicate with Anna.
Three Years Later:
Elsa (now voiced by Idina Menzel) is now 21 years old, comes of age, and the castle prepares to crown her as the kingdom's queen. Dignitaries from around Europe are coming to visit, including the Duke of Weselton (Alan Tudyk), who wants to run Arendelle's profits dry.
Elsa is nervous about emerging from her seclusion and receiving the many guests. When Elsa gives the order to open the castle gates, Anna (now voiced by Kristen Bell) eagerly rushes out into the city ("For the First Time In Forever").
As Anna strolls out onto the streets, she crashes into a horse belonging to a charming and handsome visitor, and falls into a rowboat. The visitor apologizes and introduces himself as Prince Hans of the Southern Isles (Santino Fontana), in town for Elsa's coronation. Though Anna is angered at first by Hans's clumsiness (after inadvertently falling on top of her in the rowboat due to said rowboat teetering on the side of a dock and being balanced only by a leg from Hans's horse), she seems smitten by him once she has a real good look at him. Anna runs off when she hears the church bells.
Elsa remains nervous during the coronation ceremony. The bishop (Robert Pine) has to remind her to remove her gloves before she takes up her golden orb and scepter. Holding them, she turns to face the congregation, but almost immediately panics when she sees the gold of the orb starting to frost while the bishop is bestowing her authority on her. She returns the orb and scepter hurriedly to the bishop and puts her gloves back on.
At the coronation reception a couple hours later, Kai introduces Elsa and Anna to the crowd. Anna's first friendly interaction with Elsa in years brings quite the delightful feeling to Anna, flustered at first, as well as seeing Elsa so happy instead of serious and preserved boosts Anna's confidence, prompting her to continue on with the conversation. They're interrupted afterwards by Kai introducing to them the Duke of Weselton. The Duke is a buffoon (to the point that a running gag throughout the movie is people calling his homeplace "Weasel Town"), but an important trading partner. Elsa politely declines his offer to dance with her, but instead playfully volunteers Anna, much to the Duke's delight nonetheless, and the two head off into a comical dance scene. Elsa can't resist chuckling seeing Anna get innocently flustered by the Duke's over-the-top (and incredibly terrible) dancing skills. This causes Anna to feel just as whimsical about the entire matter, for seeing Elsa in such a state hasn't been a sight for years. Anna returns by Elsa's side afterwards, commenting on how well things have been going through the day, and expresses her wishes to have things the way they were that night all the time. Elsa does agree, though her smile quickly fades away as memories of the night she froze Anna's head come floating back to the surface, and she reluctantly denies Anna's wishes all at once despite failing to explain why so.
Anna then takes to the floor with Hans. The two of them quickly sneak off to spend the evening together, quickly realizing the mutual attraction between them. The romantic dance eventually leads to an entire date ("Love is an Open Door"), with the entire night of the young couple being spent bonding. Hans, during their time together, learns of Anna's longing of having someone special in her life, with her sister apparently developing a dislike of being around her by suddenly shutting Anna out one day when they were kids. Hans openly relates to this, only furthering Anna's connection with him. Hans then promises to never shut Anna out unlike Elsa, much to the princess' absolute joy.
By the end of their tour throughout the kingdom, Hans proposes right on the spot to which Anna immediately accepts. The two head back the ballroom, where Anna asks for Elsa's blessing on the marriage. Elsa's baffled by the shocking news, but Anna and Hans couldn't appear more excited going on to ramble about the wedding arrangements. Elsa ceases the sudden rambling by denying them a marriage license, much to Anna's dismay. Elsa asks to speak to Anna alone in private, likely to finally confess her abilities and why it's not wise to marry someone she just met without causing a scene that would expose her powers, but Anna refuses any private conversation, stating whatever Elsa has to say can be said to both her and Hans. Elsa, becoming impatient and frustrated, outright refuses to let Anna marry someone she just met, indirectly telling Anna she knows nothing about true love. This causes Anna to hiss back, telling Elsa all she knows is how to shut people out. Although Elsa is visibly hurt by this, she continues to refuse, with the argument only worsening when she orders the guards to end the party early and close the gates.
Unable to contain her emotions, Elsa makes a violent sweep with her left arm, causing a barrier of sharp icicles to suddenly appear around her. Shocked at the room's reaction to her powers, Elsa rushes from the room.
Panicking, Elsa flees with Anna in hot pursuit. As she bolts out the door, she finds a huge crowd waiting for her in the courtyard. She hastily rushes through as men applaud her. A concerned woman asks Elsa if she's all right. She is frightened enough that she backs into an ornamental fountain and freezes it solid when she grabs it with her left hand. The Duke of Weselton comes out the same door moments later. Elsa pleads for people to step back, moments before another bolt of ice shoots from her hands, nearly hitting the Duke and his guards. She keeps running away, sprinting across the waters of the fjord, her feet forming an ice bridge, and vanishes into the forest on the other side of the fjord.
Anna calls after her sister, but as she, Hans, and the other guests watch, the waters of the fjord completely ice over and the air takes on an icy chill. Moments later, snow begins to fall.
The Duke of Weselton begins to panic, declaring they must take action and put an end to Elsa's curse. Anna, however, refuses and volunteers to seek out Elsa herself and make things right, feeling that it's her fault for pushing her. With Hans being left in charge of the kingdom, Anna sets out on horse to begin her search for Elsa.
Meanwhile, Elsa has found her way to a high precipice on the North Mountain, many miles from civilization. It is here she realizes that far away from what she was taught, being on her own, she can begin to control her powers ("Let it Go"). She constructs an elaborate ice palace, changes her confining wardrobe into a shimmering dress, and vows to stay in seclusion, where she feels she can be herself, and harm no one else.
The next morning, Anna is seen travelling slowly through knee-deep snow on horseback. Her journey is hindered when her horse is spooked by falling snow and runs off. She is forced to spend the rest of the day trudging through knee deep snow, all the while griping that she wishes Elsa had the ability to cover the fjords in a tropical paradise. She sighs with relief upon seeing a building with smoke coming from a chimney. Just then, Anna slips and falls into an ice-cold creek, which freezes her dress stiff. She staggers the rest of the way to the cabin with the chimney, a place known as Wandering Oaken's Trading Post and Sauna, run by its burly owner, Oaken (Chris Williams).
Anna quickly staggers into Oaken's store. He doesn't have much winter gear in stock (it's supposed to be the off season), aside from one pair of boots and a single women's mink coat. Anna inquires if Elsa has visited recently, but Oaken tells her that she's the only person crazy enough to be out in a storm like this. As if on cue, Kristoff staggers in out of the storm, seeking to buy some rope, an axe, and carrots for Sven. Oaken can't help but notice that Kristoff is bundled up tightly. Kristoff replies that there's a real howler going on up on the North Mountain. As Anna waits for Oaken to return his attention to her, Kristoff argues with Oaken over the outrageous price gouging on the items he needs (due to Oaken claiming that there's a supply and demand problem since Kristoff is buying from the almost-bare shelves of the winter department), which ends with Oaken roughly throwing Kristoff out into the snow after Kristoff makes the mistake of calling him a crook.
Kristoff and Sven take refuge in a barn on Oaken's property, but are soon met by Anna, who has bought Kristoff's supplies for him, on condition he take her up the North Mountain immediately. Kristoff eventually agrees.
Anna and Kristoff set off into the night with Sven driving. As the discussion turns to Elsa, Anna explains about her whirlwind engagement to Hans. Kristoff is incredulous at Anna's foolhardiness in getting engaged to someone she just met that day, to the point that he quizzes her about Hans to see how little she really knows about him. Their conversation is interrupted when the sled is ambushed by a pack of wolves. Kristoff is initially reluctant to let Anna assist him, but Anna proves to be useful and manages to take out a few of the wolves by herself. There is a moment of panic when the two see a gaping ravine up ahead. Kristoff hurriedly throws Anna onto Sven's back, then, just as they reach the cliff, he uses his knife to cut Sven's harness. Anna and Sven successfully clear the chasm, and Kristoff does, just barely, but his sled falls to the bottom of the ravine and explodes. Kristoff is at first upset that his sled is gone (as he'd just paid it off), but after "arguing" with Sven (which consists of Kristoff speaking his own opinion in his own voice and then delivering Sven's "counterargument" in a goofy voice), decides to help Anna keep going, worried for her safety. Anna promises she will replace the sled.
Early the next morning, Anna and Kristoff enter a frosted-over glen. They suddenly hear a new voice and meet a talking snowman named Olaf (Josh Gad). The introductions don't go smoothly, as Anna screams and kicks Olaf's head off upon first seeing him. Anna doesn't recognize Olaf until he gives his name and adds, "and I like warm hugs." This jogs Anna's memories and she remembers building him with Elsa when they were young. Anna and Kristoff mention that they're looking for Elsa so they can restore summertime, and Olaf suddenly grows excited; it's his dream to see what summer is like, and he fantasizes about what he wants to do in the summertime in a Busby-Berkeley dance number ("In Summer"). Anna and Kristoff choose not to reveal that he will melt in the summer heat, but follow him as he leads them to Elsa's ice palace.
In the late afternoon, Anna, Kristoff and Olaf arrive at Elsa's ice palace. Sven waits at the bottom of the stairway leading up to the front doors, as his feet can't get a grip on the icy steps. Meanwhile, when they get to the front door, Anna tells Kristoff and Olaf to wait outside, warning them that the last time she introduced Elsa to a guy, she froze everything (making Elsa look like an overprotective sister). The dejected Olaf and Kristoff wait outside and start counting to 60 while Anna heads inside.
Inside, Anna is stunned at the glorious interior of the palace and, even more amazed, to see the new ice dress Elsa has conjured for herself. Though Elsa is happy to see Anna and quickly forgives her for the argument that happened at the coronation party, she becomes nervous and suggests Anna leave so she can't do any harm to her. The conversation is momentarily interrupted when Olaf crashes the meeting (having taken Anna's request of "give us a minute" quite literally). Elsa is astonished to find that her powers include the ability to conjure up living snowmen.
As it turns out, Elsa is surprised to learn that her entire kingdom is frozen, and Anna is surprised in turn to learn that Elsa doesn't know how to stop it. But Anna insists her sister's powers are no reason why they should be so distant. However, having seen Olaf, Elsa flashes back to accidentally hitting Anna in the head with her snow abilities and grows scared, demanding Anna leave.
Elsa retreats to the upper portion of the palace, and Anna follows her, pleading with her sister that they can solve this problem together ("For the First Time In Forever (Reprise)"). But Elsa grows so upset that she unleashes an icy chill, of which a portion strikes Anna in her heart.
Elsa retreats to the upper portion of the palace, and Anna follows her, pleading with her sister that they can solve this problem together ("For the First Time In Forever (Reprise)"). But Anna's promising to stand by her sister's side and help her, Elsa only grows more agitated and nervous resulting in her magic flaring. This time, a blast of magic bursts out and strikes Anna in the heart. Elsa, in desperation to get her sister to safety, creates a giant snow creature (that Olaf calls "Marshmallow") to throw them out.
Marshmallow deposits Anna, Kristoff and Olaf on the front steps outside the ice palace. Though he initially leaves them alone, Anna is pissed off and quickly throws a snowball at him. Marshmallow is provoked, and chases Anna and Kristoff into the woods.
Marshmallow manages to corner them at the edge of a cliff, though Kristoff immediately begins digging a snow anchor by using a rope to safely guide himself and Anna down the mountain to safety. Marshmallow, however, catches up to them, though Olaf tries to stop him (to comically little success). Marshmallow, annoyed, kicks Olaf over the cliff, and continues his chase for Anna and Kristoff. He pulls them up to his face by the rope, and screams in their face "DON"T COME BACK!". Anna then grabs Kristoff's knife and cuts the rope. This sends the duo into freefall, onto a twenty foot deep pile of fresh snow. With his mission to drive them away complete, Marshmallow returns to the ice palace.
As they recover from the landing, Kristoff notices that Anna's hair has started to turn white. Fearful that she may be injured, Kristoff takes her to his family...who happen to be a group of rock trolls -- the same ones that saved Anna many years before. Kristoff explains that as he had no family at a young age, the trolls took him and Sven in.
The trolls are overjoyed to meet Anna, and at first they eagerly believe that she is Kristoff's steady girlfriend, so they try to marry them in a dance number ("Fixer-Upper"), and almost get all the way through the vows before being stopped by the accidental participants. However, he tells them that she is injured and needs their assistance. Just as he did 13 years ago, Grand Pabbie comes forward and examines Anna, but concludes that this time her sister's powers struck her in the heart. Pabbie cannot save her; Anna's heart has begun to freeze. Grand Pabbie says "an act of true love can melt a frozen heart." Anna quickly tells Kristoff that Hans can surely help, and they take off for Arendelle.
Meanwhile in the city, Hans has been providing shelter and help for Arendelle's people. When Anna's horse returns, riderless, Hans asks for volunteers to join him in bringing Anna back. The Duke of Weselton volunteers his two bodyguards, and secretly tells them to shoot Elsa if they should encounter her.
The next morning, Hans's party arrives at Elsa's ice castle. Shortly after they arrive, Hans orders that no harm is to come to Elsa. While everyone agrees, the Duke's thugs quietly disagree, still following the Duke's orders to kill her. The moment they come close enough, Marshmallow reveals himself from the form of snow boulders piled up by the base of the stairs, and jumps right into battle. The archer immediately attack the beast with their arrows, infuriating Marshmallow and causing his ultimate form to be unleashed. Marshmallow is able to hold most of the guards off. Hans, however, proves to be a fierce warrior himself, avoiding each of Marshmallow's attacks and eventually using his sword to slice the snow monster's leg off and cause him to lose balance and begin tumbling over to a large gorge. With Marshmallow wounded, Hans begins heading inside Elsa's castle. Marshmallow, however, doesn't give up, giving one last swing in attempt to drag Hans down with him. Marshmallow fails, and plummets down into the chasm below, apparently to his death.
While Hans has been battling Marshmallow, the Duke's two men have managed to use the distraction to barge up the ice steps and into the castle, where they corner Elsa. Despite her pleading for them to not shoot, they shoot at her. She quickly forms walls of ice as shields to block their shots. Eventually, she has the beardless thug pinned to a wall by several icicles and is on the verge of using a wall of ice to shove the bearded thug off the balcony. Hans and his men show up just in time and Hans pleads for her to stop, so she doesn't become the monster people accuse her of being. Elsa settles down a bit at Hans' words, realizing what she's doing. The guy pinned to the wall, still complying with the orders of the Duke, aims his crossbow at Elsa's head and prepares to shoot her. Hans suddenly runs over and deflects the bow. The arrow is released and hits the bolt attaching an icy chandelier to the ceiling, which begins to fall straight for Elsa's head. Elsa tries to run, but the falling chandelier fragments and knocks her unconscious.
When Elsa wakes up, she's back at the castle in a dungeon cell, her hands chained and encased in steel mitts. As she looks out over the frozen kingdom, Hans appears, telling Elsa that Anna has not returned, and pleads with her to stop the winter. Elsa claims she can't, and must be let go to keep others from being harmed.
Meanwhile, Kristoff and Sven arrive at the castle. Anna's condition has grown worse, a chill coursing through her, and more of her hair has turned white. Several of the castle staff escort her in; she looks back as Kristoff and Sven leave. Anna is brought to Hans and tells him that he has to kiss her in order to save her.
The castle staff in the room quickly leave to give them privacy. Hans places Anna in a chair, leans in as if to kiss her... and says "Oh, Anna, if only there was someone here who loved you!" As Anna looks at him in shock, Hans explains that as the youngest of 13 brothers, he had no chance at claiming his family's throne, so he went looking for a royal family he could marry into. Unable to get to Elsa, he made Anna's acquaintance and played on her naivete. He intended to marry her before causing some form of "accident" for Elsa that would clear his path to the throne.
However, given Anna's current condition, he plans to simply let her frozen heart overcome her, then stab Elsa, ending the eternal winter. Anna tries to stop Hans, but he extinguishes the fire in the nearby fireplace before locking her in the room. It is then that Anna collapses, her hair now completely white.
Hans goes to speak with the duke of Weselton and several other dignitaries. He claims that Elsa has caused Anna to freeze to death, but before she died he and Anna recited their wedding vows. This apparently is enough to give him full authority to declare Elsa guilty of treason and sentence her to death.
The palace guards go to Elsa's cell, but are detained when a wall of the cell collapses. While they are held up, Elsa freezes her shackles to the point that they shatter, and then breaks through the wall to the outside.
Meanwhile, far from Arendelle, Kristoff and Sven are trekking away when Sven urges Kristoff to go back. Kristoff claims he has no need to, but as they look back at Arendelle, a mysterious swirling cloud of snow begins to engulf the kingdom. The two then take off towards the growing danger.
Olaf has managed to find Anna in the locked room, and seeing her freezing, quickly lights a fire in the fireplace. Anna explains that Hans wasn't her true love, and that Olaf should leave or he'll melt. However, the little snowman says he will not leave her side until he finds an act of true love that can save her. As they talk, Olaf recalls how Kristoff did so much to get her back to save her, when the wind blows a window open. Olaf goes to close it, but in the distance he sees Kristoff and Sven charging towards them.
This gives Anna hope. She realizes that they're in love: maybe Kristoff can save her. Olaf helps her up, but in the hallway, ice springs up to block their path. Going out a window, the two slide down the castle's steep roofs. Anna attempts to make her way across the icy fjord, with Olaf close behind. However, as the wind picks up, Olaf is blown away, and Anna finds her hands are turning to ice. Even so, she continues to move forward, calling out Kristoff's name.
Meanwhile, Hans has found Elsa wandering the ice of the fjord. Thinking he's come for her, Elsa tells him to leave her alone, and take care of Anna. Hans lies and says that Anna was killed by Elsa's magic. The pain of this causes Elsa to collapse, the snow in the air suddenly hanging in stillness.
The clearing of the whiteout enables Kristoff to see Anna, and he runs to her, but as Anna looks around, she sees Hans about to stab Elsa. Even with her own life at stake, Anna rushes in front of Hans, blocking the knife. As she does so, her frozen heart finally consumes her, turning her into a statue of ice, and shattering Hans' blade.
Kristoff and Sven arrive seconds later. Seeing Anna turned to ice, Elsa breaks down in tears, hugging her sister. No one is sure what to say, when Anna's icy form begins to change and gain color, and she returns to normal! Anna broke her own spell: saving Elsa was an act of true love.
It is then that Elsa realizes what can end the winter: love. And with this realization, she dissipates the ice and snow, and summer returns to the kingdom. Olaf is found, and before he can melt, Elsa creates a perpetual snow flurry above his head, which lets him survive the summer heat.
In the aftermath, Hans is taken back to his kingdom by a French ambassador, who promise to see he is punished for his attempted regicide. The duke is as hotheaded as ever and tries to play the innocent victim. But remembering that he sent two men to kill her, Elsa issues a decree to sever all trade with Weselton. To piss the duke off even further, she tells the messenger to call his duchy "Weasel Town."
Meanwhile, Anna makes good on her promise and replaces Kristoff's sled. She also tells him that Elsa has appointed him the castle's official ice deliverer. Kristoff is so grateful that he kisses her. If he wonders why a queen who can conjure ice out of thin air needs ice deliveries, he keeps the question to himself.
Having come to grips with her powers and learning they can be a blessing and not a curse, Elsa uses them to create a wintry spectacle in the summer sky. She also turns the castle's courtyard into an ice rink, where she informs Anna that the gates to the castle will never be closed again. With the city's people in attendance, the sisters skate around the rink, happy that they are finally together again.
After the credits are over, we cut back to Elsa's ice palace, where it's revealed that Marshmallow survived the fall after Hans cut off his leg. Wandering through the empty ice palace, he finds the tiara that Elsa tossed away during "Let It Go", and puts it on his head, smiling to himself, and the spikes and fangs on his back quickly retract.