The two droids attempt to keep out of the way of the humans hurrying about, but soon find to their dismay that the ship has been captured. Threepio loses track of Artoo for a moment. Artoo is approached by a young woman in a white dress. She gives him something and then disappears. When Threepio finds Artoo, the little droid insists that they board an escape pod, to which Threepio reluctantly agrees.
Since the droids don't register as life readings on the Star Destroyer, the big ship ignores their escape pod, which spirals down toward the desert planet below.
The people aboard the smaller ship have been beaten. Those not killed have been taken prisoner by the white-armored soldiers of the Star Destroyer. The stormtroopers freeze, standing at attention, when a tall, helmeted figure in a black cape enters the ship. He proceeds to strangle all the information he can get from Captain Antilles, whose ship it is, but learns nothing. He orders the ship searched.
The young woman who is object of his search, Leia Organa, an Alderaanian princess and member of the Senate, is also, unknown to many, a leader of a secret movement of rebels. The crushing rule of the Empire has forced many to resist. She is eventually found, but shoots a stormtrooper before she is stunned.
When Leia is brought before Darth Vader, the black-caped figure, she shows no fear and denies connections with the Rebels. Vader, however, doesn't believe and has her locked up.
After the droids' escape pod crash lands in the midst of a sea of sand dunes, the two droids attempt to travel together, but bickering soon drives them apart. Artoo starts off for an area rock outcroppings, while Threepio sets off into the dunes. Soon, though, he becomes desperate. When he spies a speck in the distance, he assumes it is a transport and calls its attention to him.
Artoo, meanwhile, is making his way through the rocks when suddenly a small figure in a brown, hooded robe jumps out of hiding and shoots a bolt of electricity at him with a gun. Artoo, circuits overloaded, becomes "unconscious." The robed figures, Jawas, tote Artoo to their gigantic Sandcrawler, a tank-like vehicle that they use for transportation. Threepio, who also has been captured, is reunited with Artoo.
Darth Vader sends a detachment down to Tatooine to search for the plans once he discovers that an escape pod was jettisoned during the fighting. The stormtroopers find evidence of droids and begin their pursuit.
The droids are taken out some time later when they arrive at a moisture farm owned by Owen Lars. As the Jawas attempt to sell something to the grizzled farmer, his nephew, Luke Skywalker, tries unsuccessfully to get permission to go out with his friends.
Owen decides to buy Threepio and a droid similiar to Artoo. A stroke of luck occurs when the strange droid's motivator goes bad. Artoo is suggested as a substitute, and Luke is set to cleaning the droids and getting them ready to work on the farm.
Luke is a young man of nineteen years who dreams of following his friend Biggs to the Academy. He is desperate to leave Tatooine, and perks up immediately when he learns that Threepio and Artoo are involved with the Rebellion. While cleaning Artoo, he stumbles across a message, showing a hologram of a beautiful young woman.
Before Luke can find out much more than the fact that the girl needs help from someone named Obi-Wan Kenobi, Owen calls him to the evening meal. Luke questions Owen about Obi-Wan, wondering if he might be related to Ben Kenobi, an old hermit that lives out beyond the Dune Sea. Owen replies that Ben is a crazy old man, that Obi-Wan died about the same time as Luke's father, and that Luke should forget it. Luke then tries to convince Owen to allow him to apply for the Academy this year, instead the next. Owen refuses, and Luke storms out.
When he returns, he finds that Artoo has escaped. Afraid his uncle will be angry, Luke sets out with Threepio the next morning in his landspeeder to search for the little droid. They find him, but Artoo's sensors pick up several creatures nearby. Luke knows immediately that it must be the Sand People, or Tusken Raiders, a race of humanoids that lives in the desert, apart from the moistures farmers, like Owen. He tries to get a look at the Sand People, but is ambushed and knocked unconscious. Threepio falls backwards down a hill, and Artoo hides.
As the Sand People sort through Luke's provisions, they are startled by a loud noise. Though it appears to be only a robed figure approaching, they flee.
The figure approaches Luke and revives him. It turns out to be the old hermit, Ben Kenobi, who reveals that his real name is Obi-Wan Kenobi. Luke tells him of the message, and Ben decides that they should all go back to his house, since the Sand People will soon return.
At Ben's home, Luke is gifted with a lightsaber, a laser sword that belonged to Luke's father. Ben tells Luke of his father, Anakin Skywalker. Anakin was a Jedi Knight, as was Ben, part of an ancient order of honorable warriors and peacemakers who use a mystical energy field known as the Force. The Jedi were hunted down, however, with the help of a young pupil of Ben's, Darth Vader. Anakin was betrayed and murdered by Vader. Ben explains that the Force has two sides. The Jedi, the force of good, use the good side, while those who have succumbed to anger and hatred use the dark side of the Force.
Artoo plays the message for Ben. Leia, the young woman in the message, reveals that the Rebellion has obtained the plans of an Imperial battle station. Since Darth Vader attacked her ship, however, she could not get the plans to Alderaan, so she managed to get to Tatooine before the ship was boarded. Then she sent Artoo to Ben to beg his help in getting Artoo, who holds the stolen plans in his databanks, to Alderaan.
Ben decides he must undertake the mission, and tries to convince Luke to accompany him, saying that Luke must learn the ways of the Force. Luke, a bit overwhelmed, remembers his uncle and declines.
Meanwhile, on the the Imperial battle station, the Death Star, the high officers are having a meeting. While they argue, Darth Vader and Grand Moff Tarkin, the commander of the Death Star, enter and assure the officers that the stolen plans would soon be recovered. One officer angers Vader, who proceeds to demonstrate his powers in the Force by choking him. Tarkin orders him to release the hapless officer.
Back on Tatooine, Luke, who is taking Ben to Anchorhead so he can get a transport to the spaceport Mos Eisley, comes across a routed sandcrawler. He realizes that the Empire must have traced the droids to the Jawas, and therefore to his aunt and uncle. Leaving Ben and the droids, he hurries back to the farm, only to find it destroyed, and Owen and Beru, his aunt, dead.
Leia is proving more of a handful than Vader originally thought. He employs an interragation droid to force Leia to talk.
Luke, now that his guardians are dead and his home destroyed, agrees to accompany Ben to Alderaan. They journey to Mos Eisley, where they hire a Corellian freighter pilot named Han Solo to transport them to Alderaan.
After Luke and Ben take their leave, Han encounters a bounty hunter named Greedo. Greedo reminds him of his debt to Jabba, a notorious crimelord, but Han is able to shoot him.
On the Death Star, Darth Vader reports that Leia resisted the mind probe, and has not revealed the whereabouts of the plans or of the Rebels' secret base. Tarkin shrewdly decides that another form of persuasion must be employed. He decides to take the Death Star to Alderaan, Leia's home planet.
In Mos Eisley, Han encounters Jabba himself, who agrees to let Han go for fifteen percent more of his debt. Han and his copilot, the Wookiee Chewbacca, get the ship ready for take off.
Luke sells his speeder to obtain enough money to pay Han. Then he and Ben go back to the hangar bay where Han's ship, the Millenium Falcon, is located. Just after they board the ship, several stormtroopers arrive, and the Falcon is forced to make a hasty exit. A few tense moments follow as the ship prepares to make the jump to hyperspace, since it encounters two Star Destroyers. The freighter is able to escape, however.
The Death Star has arrived at Alderaan. Leia is brought out and threatened with Alderaan's destruction unless she reveals the Rebels' secret base. She names Dantooine, but Alderaan is destroyed anyway, as a demonstration of the Death Star's formidable firepower.
Ben feels the millions of deaths through the Force while Luke is practicing with his new lightsaber. Luke shows aptitude for the Force by deflecting blaster bolts while blindfolded. As the ship comes up on Alderaan, Ben congratulates him.
Tarkin is livid with anger when it is reported that Dantooine is not the current rebel base, but an old, abandoned one. He orders Leia's immediate terminatation.
Han, Luke, and Ben are bewildered when they reach the coordinates of Alderaan and find nothing. Ben realizes immediately what has happened, and when they encounter a lone Imperial TIE figher, he advises Han not to go after it. Han ignores the warning and chases the figher. They approach what looks like a small moon, but what is actually the Death Star. By the time Han realizes something is wrong, they have been caught in the station's powerful tractor beam.
When the Millenium Falcon is searched, they are nowhere to be found. Once the scanning crew has left the ship, Han, Luke, Ben, and the droids emerge from smuggling compartments in the floor that are shielding against detection. They manage to lure two stormtroopers aboard, then steal their uniforms and helmets. Disguised, they make their way to a control room. Ben sets out to disable the tractor beam, telling Han and Luke to wait for him.
Artoo discovers that Leia is aboard and scheduled to be terminated. Luke persuades Han to help him rescue her by dangling the promise of her riches in front of him. They penetrate the detention block by pretending Chewie is a prisoner. They shoot the guards and rescue the princess, but are beset by more stormtroopers before they can escape.
Meanwhile, Ben has found the tractor beam controls. He shuts it down and steals away. Eventually, he encounters Darth Vader, his former pupil, and they begin to duel with their lightsabers.
Leia shoots a hole in a vent in the wall and they all escape into the hole, only to find themselves in a garbage chamber. Luke is pulled deep into the refuse by some creature, but is released right before the garbarge masher begins to crush the refuse. Luke desperately tries to contact Threepio and Artoo, who can shut down the masher, but he can't get through.
Finally, Threepio remembers to activate his comlink, and Artoo shuts down the garbage masher in the nick of time. All goes well until they run into a squad of stormtroopers. Chewie and Han take off in one direction, and Luke and Leia flee in another. Eventually, they are reunited, and make for the Millenium Falcon.
Ben and Vader are fighting in the corridor across from the docking bay. When Ben sees that Han, Luke, and Leia have reached the ship, he straightens and salutes Vader, who cuts him down. The Falcon escapes, but Luke is devastated, and the danger is not over yet. Four sentry ships attack them, and Luke and Han man the Falcon's guns and manage to destroy them.
On the Death Star, Vader reports the Rebels' escape to Tarkin. Tarkin warns him that the homing beacon had better be secure aboard their ship.
The Millenium Falcon reaches Yavin 4, the site of the Rebels' base. Han gets his reward, but Luke asks only that he be allowed to fly a starfighter against the Death Star. The request is granted, and he soon attends a briefing that outlines a weakness in the battle station's defenses.
Luke is reunited with his old friend from Tatooine, Biggs Darklighter. He also becomes acquainted with Wedge Antilles, a young fighter pilot. The Rebels set out from Yavin 4. After three attack runs and the destruction of all but three of the fighters, Luke himself shoots the torpedoes that destroys the Death Star. Han saved him when a TIE interceptor piloted by Darth Vader himself was on his tail. Biggs is killed, but Wedge survives.
Seconds before the Death Star destroys Yavin 4, it explodes, and Luke and Han return as heroes.