The concluding episode of _Star Wars Rebels's first season, and also the fifteenth episode overall, is titled "Fire Across the Galaxy".
This episode, which was both penned by Simon Kinberg and helmed by Dave Filoni, was initially broadcast on March 2, 2015 via Disney XD.
Picking up where "Call to Action" and "Rebel Resolve" left off, this installment sees the rebels undertaking a mission to liberate their leader, Kanan Jarrus, from the clutches of the Galactic Empire. The episode features a confrontation between Imperial and rebel forces above Mustafar, the reappearance of Darth Vader and Bail Organa, a final showdown between Kanan and the Grand Inquisitor, and the revelation of Fulcrum's identity as the former Padawan Ahsoka Tano.
In a last-ditch effort, the Ghost crew endeavors to rescue Kanan from the Empire. Who will meet their end?
Sabine, Zeb, and Ezra carried out a sabotage operation at an Imperial complex on Lothal, resulting in the destruction of several TIE/ln space superiority starfighters and the acquisition of an Imperial transport. Once back on the Ghost, the crew strategized how to infiltrate the Sovereign and rescue Kanan, who was being held captive and tortured by the Grand Inquisitor in an attempt to extract information regarding the location of other Rebel cells and the true identity of "Fulcrum."
The remaining members of the crew decided to utilize the TIE fighter previously stolen by Ezra and Zeb, loading it with EMP grenades to disable the ship's power, and then dock their acquired transport with the vessel to gain entry. Meanwhile, the Grand Inquisitor tormented Kanan with recollections of his master, Depa Billaba's, demise during Order 66.
The rebels successfully infiltrated Grand Moff Tarkin's Star Destroyer, but Tarkin quickly responded to their sabotage by dispatching stormtroopers from neighboring Star Destroyers to board the Sovereign. While being pursued by stormtroopers, Ezra was compelled to separate from the others to rescue Kanan on his own. The rest of the crew tried to leave the Sovereign. Chopper, while aboard the stolen transport, contacted "Fulcrum" seeking assistance.
Ezra successfully freed Kanan from his confinement, but the Inquisitor intercepted them in the ship's reactor core room, leading to an intense duel between Kanan and the Inquisitor. While they were locked in combat, Ezra joined the fray with Kanan Jarrus' lightsaber (with his own being used by Kanan for the duel), which was attached to the Inquisitor's belt. After briefly disarming Kanan, the Inquisitor threw his lightsaber at Ezra, knocking him off the platform and rendering him unconscious.
Initially shocked and saddened by what he believed to be the "death" of his Padawan, Kanan swiftly regained his composure and fought the Inquisitor with renewed determination. He destroyed the Grand Inquisitor's lightsaber and forced him to cling to the edge of the platform. The discarded lightsaber then plummeted into the Sovereign's reactor core, triggering its destruction and setting off a chain reaction. Before releasing his grip and falling to his death, the Inquisitor warned Kanan that "there are things far worse than death."
Ezra, who was merely unconscious rather than deceased, was reunited with a relieved Kanan. Hera, Zeb, and Sabine, having made their way back to the TIE fighter they had used to infiltrate the Sovereign, escaped the Star Destroyer only to discover that Chopper and their transport were missing. Kanan and Ezra commandeered the Inquisitor's TIE Advanced and rejoined their comrades, who were now stranded in space without Chopper. Tarkin ordered the evacuation of the Sovereign, which was rapidly disintegrating. During the ensuing space battle, the crew of the Ghost realized the impossibility of escape. At the last possible moment, Chopper reappeared with the transport, the Ghost, and three Corellian Corvettes. Following the docking of the TIEs with the transport, the fleet managed to escape from the Imperial flotilla.
Hera was reunited with Kanan and they received a message from Bail Organa, who revealed that they were just one of many cells engaged in fighting against the Empire. Ahsoka Tano then emerged from the dorsal turret of the Ghost, introducing herself as "Fulcrum." She indicated a shift in strategy. Upon returning to Lothal, Tarkin met with Agent Kallus, who informed him of an impending rebellion as the populace perceived the Empire as weak and vulnerable. Tarkin reassured Kallus that the Emperor had dispatched an alternative solution: Darth Vader.