Luke goes to put handcuffs on Chewbacca, but the great beast growls at him, so Luke tells Solo to do it instead. 3PO asks what he and R2 should do, and Luke tells him to lock the door.
Dressed as stormtroopers, Luke and Solo lead Chewbacca down a long hallway, as though he were a prisoner. They climb aboard an elevator and travel to the fifth floor where Leia is being held. Meanwhile, Obi-Wan goes in search of the generator.
On the fifth floor, a commander asks where Luke and Solo are taking Chewbacca, and says that he has to clear it. Suddenly, Chewbacca attacks the guards walking towards him, and Luke and Solo shoot the remaining guards with blaster pistols. They then shoot the security cameras and Luke makes his way to Leia's cell, while Chewbacca and Solo stay behind. Solo averts any broader intervention by telling someone on the intercom that they've just had a slight weapons malfunction, but that everything is fine. The person on the intercom is skeptical, so Solo shoots the intercom and yells to Luke that they are going to have company soon.
Luke runs down the hall and finds Princess Leia asleep in her cell. When she sees him she simply says, "Aren't you a little short for a stormtrooper?" and he takes off his helmet and introduces himself. He tells Leia he's there to rescue her and that Ben Kenobi is on the ship. They rush off.
Meanwhile, Vader tells Tarkin that he can sense Obi-Wan's presence on the Death Star. "Surely he must be dead by now," Tarkin says, but Vader insists that they ought not underestimate the Force. Suddenly, they get a message from a commander that the detention center has been breached by unknown intruders. "Obi-Wan is here. The Force is with him," Vader says, and tells Tarkin that he must face the Jedi alone.
Luke, Leia, Chewbacca, and Solo escape into a long corridor, and try communicating with C-3PO who tells them that all entrances and exits except the main one are blocked. As 3PO communicates with them, someone begins tapping on the door of the command center.
With no other options, the group escapes through a small hole that Leia shoots in a nearby vent. It turns out the hole leads to a trash compactor. Suddenly, Luke feels something swimming around in the debris, a serpentine creature that wraps around Luke's leg and drags him under into the trash water. Eventually Luke emerges with the serpent-like tube wrapped around his neck, then gets pulled back under. Luke comes up to the surface just as the trash compactor begins to close in on them. He calls frantically to 3PO, but gets no answer.
When the stormtroopers find the two droids in the command center, 3PO tells them that they are hostages of the Death Star intruders, and sends the troopers on a mission to catch them. One stormtrooper stands guard, but 3PO gets past him by telling him that he wants to take R2 down to maintenance.
In the trash compactor, the walls are closing in, as they call for 3PO. He finally answers just in time for R2 to shut down the trash compactor. As it stops, they scream in delight. C3PO thinks they have died, but then realizes they are excited, and opens the hatch for them to escape.
Having escaped from the trash compactor, Leia and Solo spar about who is in charge of the operation. Leia does not take orders from Solo and refers to Chewbacca as a "walking carpet," much to Solo's annoyance.
Meanwhile, Obi-Wan makes his way to the generator and turns it off, unseen by the stormtroopers. When two begin to suspect that something might be happening, he uses the Force to move their attention elsewhere.
Rounding a corner, Solo, Luke, Leia and Chewbacca run into a group of stormtroopers and Solo starts shooting at them. "He certainly has a lot of courage," Leia says, admiringly, as Luke grabs her arm and they run in the opposite direction. They arrive at a large air shaft and Luke blasts the control panel, so that the stormtroopers cannot get through the door to them. Unfortunately, the control panel is the only way that he and Leia can extend the bridge to get across the air shaft, so they have to start thinking of other options.
As stormtroopers begin shooting at them from a portal across the air shaft, Luke pulls out a cable and hook to launch them across the shaft. They swing across to the other side to safety.
Obi-Wan walks down a corridor, where he finds Darth Vader waiting for him with a lightsaber. They begin to fight, Obi-Wan fighting with a blue lightsaber and Vader fighting with a red one. "You can't win, Darth. You can strike me down, but I will become more powerful than you can possibly imagine," Obi-Wan says, as they continue to fight.
Right near the Millennium Falcon, Luke, Leia, Chewbacca, and Solo all reconvene. They discuss what to do about the stormtroopers surrounding the ship. When the stormtroopers see Obi-Wan and Vader fighting nearby, they rush over to help, making way for the protagonists to board the Millennium Falcon. Along with the droids, they go towards the ship, but Luke peels off when he sees Obi-Wan fighting Vader.
When Obi-Wan spots Luke, he smiles and surrenders, and Vader strikes him down suddenly. Luke cries out as Obi-Wan falls, but it's too late. He shoots at the stormtroopers, but Solo and Leia call for him to get on the ship. As they escape, Vader steps on Obi-Wan's cloak, but curiously enough, finds nobody there. Luke hears Obi-Wan's voice telling him to "run" and he gets on the Millennium Falcon, which takes off almost immediately.
On the ship, Luke mourns Obi-Wan's death, as Leia assures him that there was nothing he could do. Suddenly, Solo comes in and tells them that there are Imperial fighters chasing them, and he and Luke go into the fighter cockpits to shoot them down, which they do successfully.
While the film is firmly in the science fiction genre, it has certain trappings of a classic fairy tale. The Force is a kind of surrogate for the magic of fables, and Luke's hero's journey is reminiscent of a knightly quest, as he travels to enemy territory to rescue a princess in peril. The characters are archetypal, much like the characters in such a tale, with Luke standing in for the brave rescuer, Han Solo the snarky comic relief, Leia the intelligent princess, and Obi-Wan Kenobi for a sage wizard.
Complicating the plot is the fact that Vader, in spite of being one of the most powerful villains, is connected to Obi-Wan and Luke through his common experience of the Force. While the other Imperial officers are skeptical about the Force and its influence, Vader trusts in the Force, and has chosen to harness it for his evil purposes. Certain events and factors that go over the heads of other Imperial officers do not elude Vader, who still trusts in the Force to guide him.
Around every corner lurks another danger on the Death Star. Just when Luke, Leia, Han Solo, and Chewbacca think they have evaded the stormtroopers, they find themselves in the trash compactor of the space station, which is not only filled with trash, but home to an aggressive serpent-like creature that attacks Luke. Then, when they think they are safe once again, the trash compactor begins to close to compact the trash (and them). Hazards abound on the Death Star, and a great deal of suspense is built in seeing how the protagonists will wiggle free from harm.
In the midst of all this adventure, the protagonists, who do not know each other very well and have been thrown together by circumstance, begin to get to know each other and develop distinct dynamics. The wide-eyed Luke resents Han Solo's cynicism, but Solo and Leia strike up a contentious chemistry soon enough. Each of them has a biting wit and a desire to call the shots, sparring with each other like a couple from an old Hollywood movie. Meanwhile, Leia looks to the sensitive Luke for more emotional support and a more team-oriented attitude.
Luke must take on a great deal more responsibility when he watches his mentor, Obi-Wan Kenobi, die at the hands of Darth Vader. In the lightsaber duel, Obi-Wan warns Vader that if he strikes him down, he will only become more powerful, and in the moment before he dies, it almost looks as though he is resigning himself to being killed, evaporating into thin air, leaving only his cloak behind. Luke is heartbroken in the aftermath, but Obi-Wan remains with him in spirit, even whispering to him from the ether before he boards the Millennium Falcon.