The opening crawl reveals that the Galactic Empire is building a new armored space station which is even larger and more powerful than the first Death Star.
Near the forest moon of Endor the new Death Star is being constructed in orbit, and a command star destroyer arrives and launches a shuttle with a fighter escort -- a shuttle bearing the Dark Lord of the Sith. Fearing his arrival, the crew aboard the new Death Star informs Darth Vader (David Prowse
, voice: James Earl Jones
) that the station will be operational on schedule, this despite the need for more men to accelerate construction. Darth Vader, however, informs the commander that the Emperor (Ian McDiarmid
) will be arriving soon, and that he is most displeased with the commander's progress. Shaken, the commander commits to redoubling construction efforts. Vader, pleased, remarks, "the Emperor is not as forgiving as I am."
Jedi Knight Luke Skywalker (Mark Hamill
), Chewbacca (Peter Mayhew
), Lando Calrissian (Billy Dee Williams
), Princess Leia Organa (Carrie Fisher
), C-3PO (Anthony Daniels
), and R2-D2 (Kenny Baker
) return to Tatooine to rescue Han Solo (who was encased in carbonite at the end of Star Wars: Episode V - The Empire Strikes Back
) from the gangster Jabba the Hutt (voice: Larry Ward
). Disguised as a bounty hunter named Boushh, Leia attempts to free Solo, only to be discovered and captured by Jabba, who keeps her on display in a metal bikini. Several days later, Luke arrives to make a final plea to Jabba to release Solo. Luke is also captured and is sent with Solo and the others to be slowly consumed by the Sarlacc (a huge, shark-toothed, tentacled maw at the bottom of the Great Pit of Carkoon). With the help of R2-D2, Luke escapes and a battle erupts. During the battle, Leia strangles Jabba and Solo accidentally knocks Boba Fett (Jeremy Bulloch
) into the Sarlacc pit. Luke, on Jabba's sail barge, aims the deck cannon at the vehicle and it blows apart. Our heroes manage to escape before it explodes.
A massive fleet of fighters completely surrounds the boarding bays of the Death Star at the arrival of the Emperor. As Red Guards slowly descend from the Imperial Shuttle and flank its ramp, Vader and the Death Star commander kneel to their master, the last to enter the hangar. He insists that Lord Vader will soon capture Luke Skywalker, and Luke will learn of the Dark Side of the Force.
Luke returns to Dagobah to complete his Jedi training, but he finds Yoda (voice: Frank Oz
) is ill. He tells Luke that no further training is required and all that remains to be done is to confront his father, Darth Vader. Yoda dies. The spirit of Obi-Wan Kenobi (Alec Guinness
) confronts a distraught Luke, confirming that Vader was once Anakin Skywalker, a former Jedi who was turned to the dark side of the Force. It is also revealed that Leia is Luke's twin sister, hidden from Anakin and separated from Luke at birth to protect them both from the Emperor.
Meanwhile, the entire Rebel Alliance is meeting to devise an attack strategy. As part of the attack, Luke and his companions (whom he rejoins after leaving Dagobah) must land on the forest moon of Endor and deactivate the generator that projects a protective shield up to the orbiting and incomplete Death Star. On Endor, Luke and his companions encounter a tribe of Ewoks, short, furry, intelligent forest people. An Ewok called Wicket (Warwick Davis
) befriends Leia, but other Ewoks capture the rest of the Rebel party and decide to sacrifice them to C-3P0, who they believe is a god. Luke, having mastered the Force, levitates C-3P0 to impress the Ewoks with the droid's power and scare them into giving up the sacrifice. With the help of C-3PO, Luke and his party form an alliance with the Ewoks, whose stone-age technology has unexpectedly effective military applications. Later, Luke decides that the time has come for him to face Vader. He confesses to Leia that he is her brother, and that he has to try to save the man who was once their father. He surrenders peacefully to Vader but fails to convince his father to abandon the dark side.
They go to the Death Star to meet the Emperor, who reveals that the Rebel Alliance is walking into a trap. On the forest moon, the Rebels led by Solo and Leia enter the shield generator control facility only to be taken prisoner by waiting Imperial forces. Once they are led out of the bunker, however, the Ewoks spring a surprise counterattack. In a desperate ground battle, the Rebels and Ewoks fight the Imperial forces. Aboard the Death Star, the Emperor attempts to seduce Luke with the powers of the Dark Side, and he unleashes the battle station's destructive power on the Rebel fleet. As Luke's anger builds he attacks the Emperor with his lightsaber, only to be stopped by the crimson blade of Vader's lightsaber.
During the strike team's assault, the Rebel fleet emerges from hyperspace for the battle over Endor, only to discover that the shield of the Death Star is still functioning. An intense space battle takes place as the Rebel fleet battles to give the surface party more time to deactivate the Death Star's shield. During the battle, the Death Star is revealed to be operational; its superlaser is fired at the Rebel fleet and obliterates a Rebel star cruiser.
On the Death Star, the Emperor tempts Luke to give in to his anger. A ferocious lightsaber duel erupts between Luke and his father. In the midst of combat, Vader reads Luke's feelings and learns that Luke has a twin sister. When Vader toys with the notion of turning Leia to the dark side, Luke gives in to his anger and gains the upper hand in the battle, slicing off Vader's right robotic hand in a rage in one swift cut, and makes his father succumb to defeat at the mercy of his son's blade. Despite the Emperor's goading Luke refuses to kill his father, realizing that he is traveling down his father's path towards the dark side, and declares himself a Jedi. Realizing that Luke cannot be turned, the Emperor uses Force lightning against him to torture and attempt to kill him. Deeply affected by the sight of his son dying before him, Vader repents and turns on the Emperor, throwing him down a reactor shaft to his death. At the same time, however, the Emperor's Force lightning causes fatal injuries to Vader (Anakin) and short-circuits his breathing system. Knowing that there is no hope for his own survival, Anakin asks Luke to take his mask off. Luke removes the helmet, revealing the pale and scarred face of his father. Anakin says that Luke was right about him, and asks Luke to tell his sister this. With those final words, Anakin dies.
Back on Endor, the strike team finally destroys the shield generator. The Rebel fleet seizes the opportunity to launch a final assault on the Death Star in space. Lando leads Wedge Antilles (Denis Lawson
) and his fighter group into the bowels of the Death Star where they fire at the main reactor, causing its collapse. Luke, with the body and armor of Anakin, escapes the Death Star in an Imperial shuttle. Moments later, Wedge in his X-Wing and Lando in the Millennium Falcon emerge from the Death Star as well, just as the Death Star explodes. Back on Endor, Leia reassures Han Solo of her love and reveals to him that Luke is actually her brother. That evening, Luke cremates the remains of his father in a funeral pyre on Endor. The entire galaxy celebrates the fall of the Emperor and the Rebel victory over the Empire. On Endor, Luke, Leia, Han, Lando, and the rest of the rebels, along with the Ewoks, celebrate the victory as well. During the celebration, Luke catches sight of the spirit figures of Obi-Wan Kenobi, Yoda and the redeemed Anakin Skywalker, who look proudly upon him.