Perry the Rebelpus bursts into the Imperial Corporate Offices, steals a disc containing the Death Star plans, and makes a quick, coordinated rendezvous with Princess Leia’s ship. On the desert world of Tatooine, Phineas Flynn and Ferb Fletcher live a peaceful life with their parents as contented moisture farmers, quietly passing the days in a routine that feels safe and familiar. The galaxy, however, is anything but calm. Darth Vader’s Star Destroyer closes in on Leia’s ship, forcing Leia to stash the crucial disc inside R2-D2. Their moment of hope is interrupted as a trio of Imperial stormtroopers—Candace Flynn, Baljeet Rai, and Buford Van Stomm—observe the escape attempt. Candace, eager to prove herself to the Empire, tries to report the Rebels’ actions but is promptly brushed off by her commanding officer. The moment R2-D2 and C-3PO slip into an escape pod, the stormtroopers decide to pursue them in a second pod, hoping to reclaim the plans and demonstrate their own worth to the regime, while Perry secretly tags along.
Meanwhile, the rogue Heinz Darthenshmirtz arrives at the Death Star with his robotic aide Norm-3PO, revealing a new invention that is even more evil—one that would require the Force to power it. Candace, Baljeet, and Buford dog the trail of the droids but are redirected by their commander into Mos Eisley, where the larger chase continues. Perry, ever the opportunist, trails the droids as they’re snatched by Jawas and sold to Owen Lars, and eventually Perry slips away with R2-D2. The journey soon intersects with Phineas and Ferb, who are on a path toward Obi-Wan Kenobi’s acquaintance—an old mentor who has offered them guidance in the Jedi arts. Although Obi-Wan offers them a ride, R2-D2 presses on, leaving Perry unseen by the brothers; their collision with Perry’s ride leaves the Death Star disc safely in Phineas and Ferb’s back seat.
Discovering the disc’s significance, Phineas and Ferb press forward to return it to R2-D2, their odyssey taking them to Mos Eisley. There they meet Blatto, Watto’s son, whose help becomes crucial in uncovering that the disc indeed contains the Death Star plans. The pursuit thickens as Candace, Baljeet, and Buford catch sight of the brothers, forcing a tense chase through the spaceport. The trio narrowly misses R2-D2’s departure with Luke, Obi-Wan, C-3PO, Han Solo, and Chewbacca aboard the Millennium Falcon, a moment that pushes Phineas and Ferb deeper into the larger struggle unfolding around them. Isabella Garcia-Shapiro, captain of the Centennial Chihuahua and a rival of Han Solo, enters the scene and offers to transport the boys, though she hesitates to fully commit to the Rebel cause until a moment of frank conversation with Han and Chewbacca shifts her view. She ultimately agrees to help, and Candace, Baljeet, and Buford find themselves redirected back toward the Death Star.
As the plot advances, Darthenshmirtz studies how to siphon Force energy from Darth Vader’s trash, a ploy that foreshadows the cascade of peril as Alderaan’s fate looms. The Chihuahua closes the gap with the Millennium Falcon, only to be captured in a tractor beam; a clever ruse by Phineas and Isabella allows the ship to disguise itself as a doughnut vendor, freeing the craft and the crew. Inside the Death Star’s labyrinth, Phineas and Ferb unexpectedly reunite with Perry, their former pet-turned-rebel ally, an initial flash of discomfort giving way to a shared resolve against the Empire. Perry makes his way to Darthenshmirtz’s lair, but is captured and encased in carbonite as Darthenshmirtz unveils a Sith-inator—an invention that would grant him Sith power even beyond Vader’s formidable reach. Ferb, sensing through the Force that Perry is in danger, leaves Phineas and Isabella to come to his aid, a decision that foreshadows an encounter with Obi-Wan Kenobi along the way. Ferb’s sacrifice appears to alter him in the moment, turning his gaze toward darker, more Sith-like powers and causing a dramatic transformation that includes a startling yellow iris—mirroring a pivotal moment from a different legend.
Back on the Death Star, Isabella and Phineas press forward. Isabella travels to Yavin with the Death Star plans, reframing her stance after a tense conversation with Han Solo and Chewbacca and deciding to rejoin the Rebel cause, ultimately encouraging Han to return to the fight. Candace, Baljeet, and Buford also throw in with the Rebels, choosing to stand against the tyranny that plagues the galaxy. The battles intensify as Perry and Darthenshmirtz clash with Phineas and Ferb, their actions crossing paths in ways that threaten to destabilize the entire operation. The decisive moment arrives when the Sith-inator is destroyed, restoring Ferb to normal and allowing the group—now joined by Baljeet and Buford—to race for the departing transport that brought the stormtroopers to the Death Star, only to see it depart before they can reach safety. Perry, meanwhile, exits with a carbonite-encased Darthenshmirtz, while the Rebels launch their assault against the battle station.
Left adrift on a station spiraling toward doom, Candace learns a surprising truth—that Phineas is her baby brother and that Ferb is their mother’s new partner in a shared life. Before Phineas can fully explain, the Death Star begins its catastrophic destruction, a nod to the complexities of family history within a galaxy that has no shortage of upheaval. Isabella returns just in time to rescue the group, while the Firestar Girls coordinate a last-ditch effort to evacuate civilian personnel from the orbiting menace. Darthenshmirtz escapes Perry’s ship in a small escape pod, while Perry heads to Yavin to join the celebratory mood following the Death Star’s fall. The Rebels end their day with a jubilant celebration, culminating in a dance party where Isabella’s kiss marks a moment of peace and possibility amid the chaos of war and wonder across a galaxy far, far away.
