Three years after the destruction of the Death Star, the Rebel Alliance, led by Princess Leia, has set up a new base on the ice planet Hoth. The Imperial fleet, led by a merciless Darth Vader, hunts for the new Rebel base by dispatching probe droids across the galaxy. Luke Skywalker is captured by a wampa while investigating one such probe, but manages to escape from its lair using the Force and his lightsaber. Before Luke succumbs to hypothermia, the Force spirit of his deceased mentor, Obi-Wan Kenobi, instructs him to go to the swamp planet Dagobah to train under Jedi Master Yoda. Han Solo discovers Luke and manages to keep him alive by keeping him under the body fat of his dead Tauntaun mount, and the two are rescued by a search party the following morning.
The probe alerts the Imperial fleet to the Rebels’ location. The Empire launches a large-scale attack using AT-AT walkers to capture the base, which forces the Rebels to evacuate. Han and Leia escape with C-3PO and Chewbacca on the Millennium Falcon, but the ship’s hyperdrive malfunctions. They hide in an asteroid field, where Han and Leia grow closer amidst the tensions. Several bounty hunters, summoned by Vader, assist in searching for the Falcon. Meanwhile, Luke travels with R2-D2 in his X-wing fighter to Dagobah, where he crash-lands. He meets a diminutive creature who reveals himself to be Yoda; who reluctantly accepts Luke as his apprentice after conferring with Obi-Wan’s spirit. Luke learns more about the Force from Yoda, who lifts his X-wing out of the swamp using the Force.
After evading the Imperial fleet, Han’s group travels to the floating Cloud City on the planet Bespin, which is governed by Han’s old friend Lando Calrissian. Bounty hunter Boba Fett tracks the Falcon and, with Vader, forces Lando to hand the group over to the Empire. Vader plans to use the group as bait to lure Luke, intending to capture him and turn him to the dark side of the Force. Luke experiences a premonition of Han and Leia in pain and, against the wishes of Yoda and Obi-Wan, abandons his training to rescue them.
Vader intends to hold Luke in suspended animation by imprisoning him in carbonite, selecting Han to be frozen as an experiment. Han survives the process and is given to Fett, who plans to collect a bounty on him from Jabba the Hutt. Lando, still loyal to Han, frees Leia and Chewbacca, but they are too late to stop Fett from departing with Solo. Under attack from stormtroopers, they fight their way back to the Falcon and flee the city. Meanwhile, Luke arrives and engages Vader in a lightsaber duel that leads them over the city’s central air shaft. Vader severs Luke’s right hand, disarming him, and tempts him to embrace his anger and join the dark side. Luke accuses Vader of murdering his father, but Vader reveals that he is Luke’s father. Horrified, Luke drops into the air shaft and is ejected beneath the floating city, where he hangs from an antenna. He reaches out telepathically to Leia, who senses him and persuades Lando and Chewie to turn back. After Luke is brought aboard, they are chased by TIE fighters towards Vader on his Star Destroyer and find that the Falcon’s hyperdrive has been tampered with, but R2-D2 reactivates it, allowing them to escape.
Luke rejoins the Rebel fleet and his severed hand is replaced with a robotic prosthesis. Lando and Chewbacca begin their quest to save Han, as the other rebels watch the Falcon depart.