Once there was a holy man called the Skywalker who discovered an energy field which could influence the destiny of all living things. Known as "the force of others", it consists of a good half (the Ashla), which the Skywalker came to know, and an evil part (the Bogan) which he was able to resist. His powers grew strong, helping him to found the Republic Galactica, but since the Bogan can bring much suffering in the hands of someone weak, he entrusted his secret only to his twelve children.
For many thousand years, the descendants of the Skywalker (known as the Jedi Bendu of the Ashla) served the force of others and brought peace to the galaxy. As the Republic grew, however, the Great Senate became corrupted, and the Jedi who interfered were denounced as traitors. Wars and terrorism increased to the point where citizens welcomed a police state, and the tyrannical First Galactic Empire was born. A Jedi named Darklighter fell victim to the Bogan, teaching its evil ways to a pirate clan known as the Black Knights of the Sith, who became Imperial servants and hunted down and killed most of the Jedi. Now, a growing rebel Alliance led by the Starkiller (a surviving Jedi) has won a crucial victory over the Imperial fleet, but the Bogan is very strong, weakening the old Jedi. However, according to the prophecies, a saviour shall come – known as "the son of the suns".
Deak and Clieg, sons of the Starkiller, are on their way to their brother Luke on the planet Utapau, sent by their father to retrieve the diamond-like "Kiber Crystal" which a Jedi can use to intensify either side of the force a hundred fold. However, their ship is boarded by Lord Darth Vader (a Black Knight of the Sith) and his stormtroopers, and Clieg is killed. Vader believes that Deak is the last son of the Starkiller, and as Deak wears his father's crest, the Lord takes for granted that the Starkiller is dead, and that he has altered destiny by capturing "the son of the suns". Vader orders the attack of the rebel base on Ogana Major, not knowing that Artoo Detoo and See Threepio, two of Deak's robots (or "droids"), have escaped to Utapau in order to bring a message to Luke. After a run-in with some filthy "Jawa" scavengers, they reach the farm where Luke lives with his two younger brothers Biggs and Windy, his Uncle Owen Lars and Aunt Beru, and their daughter Leia. Luke has never met his legendary father, and when he learns that he must bring the crystal to him he feels intimidated. Owen has taught Luke the ways of a skilled warrior (including the "laser sword"), but the spiritual ways of the Jedi can be taught only by his father.
Accepting his destiny, Luke takes the crystal and leaves with the droids for the spaceport at Mos Eisley. There, Luke is forced to use his laser sword against three drunken creatures in a cantina, impressing Han Solo (who claims to be a starpilot) and his companion Chewbacca (a "Wookiee" creature), who offer Luke passage to Ogana Major for a huge sum of money. Han, who is merely a cabin boy, fakes a reactor failure on board his Captain Oxus's ship, tricking Oxus (and the crewman Jabba the Hutt) into evacuating. Han and Chewbacca, together with the ship's science officer Montross Holdaack, then lift off with Luke and the droids. They reach Ogana Major only to find it completely destroyed.
Believing his father is dead, Luke assures Han that his brother Deak will provide payment for the passage – but they will have to rescue him from the Imperial dungeons of Alderaan. Approaching Alderaan, they hide in secret compartments as the ship is towed inside the Imperial city. Their ship is searched without result, as Han and Luke take out two troopers and steal their uniforms. Montross stays behind as Han, Luke, Chewbacca (posing as a prisoner), and the droids leave for the detention area. They find the tortured Deak, and after escaping a horrible dungeon monster, Chewbacca manages to bring him back to the hangar. Luke and Han, however, are cornered by Sith knights and forced to jump down a debris chute, ending up in a garbage room, where they are about to be crushed when the droids rescue them. They reach the ship and blast off into space, defeating their pursuers in a dogfight.
As Luke uses the Kiber Crystal to heal his brother, he receives a mental message from his father, telling him to come to the new rebel base on the fourth moon of Yavin. On the jungle moon, Luke meets his wizened old father for the first time, but the "Death Star" (the battle station which destroyed Ogana Major) is approaching, and Luke's Jedi training will have to wait. An assault on the station is organized, but Han, content with his momentous reward, leaves with Chewbacca and Montross, refusing to help. With Threepio and the ranger Bail Antilles as his gunners, Luke pilots one of the rebel ships attacking the Death Star, while his father uses the crystal to fight the Bogan. Sensing the Ashla, Lord Vader realizes that the Starkiller is alive, and joins the battle in his own fighter. He is just about to destroy Luke's ship, when Han reappears, sending the Sith knight to his doom. In a final attempt, both Threepio and Antilles manage to hit the station's weak point, reducing the mighty fortress to space dust. Back at the base, the heroes are greeted by the Starkiller who praises their victory as the start of the revolution.