"Zero Hour" is the two-part Season 3 finale of Star Wars Rebels. It comprises of the show's fifty-eight and nine episodes and are the collective twenty-first and second episodes of the third season. It premiered on March 25, 2017.
Thrawn arrived on Lothal with some urgent news. Taking it up in secrecy, he briefed Govenor Pryce, Admiral Konstantine and Grand Moff Tarkin, via hologram, of his findings. He had discovered the Rebels' plan to assault their Imperial TIE Defender factory on Lothal. He had also received word from his spies that General Dodonna's fleet was on route to reinforce Phoenix Squadron, but still had yet to uncover the location of their base. Govenor Pryce found a coordinated attack by multiple Rebel cells unprecedented, but was also the moment that Thrawn had been waiting for to wipe out the Rebellion. Using a Mouse Droid to listen in, Kallus heard everything and immediately headed for Ezra's Tower, where he had been sending his "Fulcrum" messages, to warn the Rebellion. However, before he could send out the details he discovered that he had been followed when Thrawn showed up in the doorway. He tackled the Grand Admiral in a fist fight, but his skills were outmatched and was easily beaten. After a brutally interrogation, Thrawn managed to pinpoint the precise location of the Rebel base, and had the fleet deployed to Atollon.
Meanwhile on Atollon, Phoenix Squadron was all prepared for their attack on Lothal, However, upon General Dodonna's arrival, Kallus was able to send his message to the Rebels before he was captured. The only thing he was able to send out was that "Thrawn knows". They immediately suspected that Thrawn knew where they were, and it was confirmed when they received word from Ryder Azadi that the Imperial fleet over Lothal had just left. The Rebels were forced to scrub their mission and evacuate Chopper Base, just as Imperial Star Destroyers emerged from hyperspace. General Dodonna's fleet attempted to escape, but they were pulled out of hyperspace by two Imperial Interdictor vessels. Just then, Thrawn's ship arrived and contacted Chopper Base. Hera refused to cooperate on any of Thrawn's terms, but Thrawn had no intention of taking prisoners. After a brief conversation with Thrawn, Hera conjured up a plan to call for reinforcements and help them escape. She suggested that by disabling one of the Interdictors, they would have a chance to allow one ship to escape. Hera volunteered Ezra and Kanan to take the Gauntlet Fighter, however Kanan choose to stay in hopes of finding some help. So it was just Ezra who would go, accompanied by Chopper.
The Ghost and the Gauntlet showed up with the fleet, just as Commander Sato launched the first squad of fighters. Thrawn had the TIEs deployed and the battle begins. Back on Atollon, Kanan went to Bendu and plead for his help in fighting off the Empire. However, Bendu was furious with what the Rebellion had brought upon his peaceful world, and refused to assist them in their fight. The Rebel fleet was even having a harder time trying to take on the Imperials, and with one of the Interdictors still cutting them off, Ezra and Chopper could not escape. Already the Rebels were losing a lot of ships. So Sato choose to sacrifice himself by colliding his ship into one of the Interdicators. He succeeded and took Admiral Konstantine with him, who tried to intercept against Thrawn's orders. With one of the Interdicators out, Ezra and Chopper were able to escape to hyperspace. Thrawn was furious by Konstantine's carelessness, and had the Rebel fleet forced to retreat back to Atollon. Meanwhile, Kanan was still unable to to convince Bendu to help, and after calling him a coward he disappeared in rage.
Travelling through hyperspace, Ezra made contact with Mon Mothma and plead for her help. However, she felt hopeless in this matter, and deeply regreted engaging in open warfare against the Empire so soon. Ezra on the other hand refused to give up, and set a course for Krownest to enlist Sabine's help.
The Rebels remained trapped on Atollon with the Imperial fleet still blocking their escape. They power up a shield around the base for protection, and only hope that it would hold. All while Kanan made his way back to base, Thrawn commenced an orbital bombardment upon the base. The shield held, but barely until Thrawn ceased fire. At the same time, Kanan noticed a storm brewing, which made him suspect that something was coming. Meanwhile, Ezra made it to Krownest and informed Sabine about Thrawn's ambush on Atollon. He asked her and the Mandalorians for help, only to be told he had come at a bad time. They were in the middle of a civil war against Clan Saxon. Despite this, Ursa was willing to hear Ezra out. Observing the problem, the Mandalorians did not see any chance of them succeeding. However, Sabine stood by Ezra and strongly believed there was a way to save the Rebellion. Ursa, who was grateful for Ezra and his friends bringing Sabine back to her, stood by her daughter's side. With only minimal resources to spare, Sabine came up with a plan that would not require a whole army to take on the blockade.
Back on Atollon, Thrawn led a ground assault on the surface, while Govenor Pryce remained in command of the fleet. The Rebels were ready for Thrawn, and engaged their walkers. Kanan joined in the fight, and made his way back to Chopper Base with Zeb and Rex for one last attempt to evacuate. Just then, Ezra and Chopper returned with Mandalorian reinforcements. Leading the fighters, Fenn Rau engaged the Imperials while Ezra and Sabine attempted to lead a strike team to take out the last Interdictor. They informed the Rebellion of their arrival, and they made no a haste to evacuate the base. Suddenly, the Imperials took out their shield generator and Hera, Kanan, Zeb, Rex, AP-5 and Dodonna became surrounded by Thrawn's men. As Thrawn believed to have won the battle, the storm earlier on drew closer. Suddenly, intense lighting struck the base. It was Bendu who had come to bring death upon both the Rebels and Imperials.
Meanwhile, Ezra and Sabine led a strike team on the haul of the last Interdictor. They attacked the gravity generators, and Governor Pryce ordered an attack to stop them. Back on the surface, both the Rebels and Imperials were at Bendu's mercy, who ordered them to leave his world. The Rebels retreated to their ships and took off. The Bendu attacked the Rebels with his lightning strikes, but they succeeded in leaving the planet. Thrawn ordered his forces to attack the Bendu, and they succeeded in shooting him out of the sky. As the Rebel fleet approached the blockade, Ezra and the Mandalorians succeeded in taking out the Interdictor. The Mandelorians shot missiles at one of the gravity generators, causing a chain reaction that destroyed the whole ship. Kallus escaped aboard an escape pod, and the Ghost salvaged him before jumping to hyperspace with the fleet. The Rebels had escaped leaving Thrawn and Pryce defeated.
Back on Atollon, Thrawn and his men arrived where the Bendu fell. Before shooting him and disappearing before the Grand Admiral's eyes, the Bendu revealed that in Thrawn's future he would face a cold defeat. Meanwhile, the remaining members of the Rebel fleet were on their way to Rebel Command on Yavin 4. Hera gave her thanks for Ursa's assistance, and Kallus thanked Kanan for taking him in. Even though they had suffered a crushing defeat, Kanan still had high hopes for a future where everyone was free from the Empire's reign of tyranny.
- Taylor Gray as Ezra Bridger
- Vanessa Marshall as Hera Syndulla
- Freddie Prinze, Jr. as Kanan Jarrus
- Tiya Sircar as Sabine Wren
- Steven Blum as Garazeb Orrelios Commander Woldar / Rebel Officer
- Dee Bradley Baker as Kassius Konstantine / Rebel Crewman / Imperial Technician / Captain Rex
- David Oyelowo as Alexsandr Kallus
- Tom Baker as Bendu
- Keone Young as Jun Sato
- Matthew Wood as Death Trooper / Stormtrooper
- Kevin McKidd as Fenn Rau
- Michael Bell as Jan Dodonna
- Mary E McGlynn as Arihnda Pryce
- Lars Mikkelsen as Thrawn
- Stephen Stanton as Wilhuff Tarkin / Imperial Officer / AP-5 / Mandalorian Pilot
- Dave Filoni as Green Leader
- Genevieve O'Reilly as Mon Mothma
- Clancy Brown as Ryder Azadi / Rebel Pilot #2
- Nathan Kress as Wedge Antilles
- Sharmila Devar as Ursa Wren
- Ritesh Rajan as Tristan Wren
- The Death Troopers debut in this episode. They first appeared in Rogue One: A Star Wars Story.
- The Death Troopers that accompany Thrawn have incandescent spots on their helmets, which were part of Rogue One's costume design, but were ultimately left unlit in the finished film.
- Jun Sato and Kassius Konstantine are killed off in this episode.
- This also brings an end to Phoenix Squadron.
- This marks the last appearance of Chopper Base, Kanan's Speeder Bike, and Phoenix Nest.
- Michael Bell, the voice actor of Jan Dodonna, was the voice of Commander Willard in Star Wars: A New Hope.
- This marks the first appearance of standardized Interdictor Cruisers. They are not to be confused with Imperial Interdictor, seen in Season 2.
- Sato's "Defense Formation Aurek One" gets its name from the first letter of the aurebesh alphabet.
- The evacuation signal Hera gives, "Kay One Zero", is the same code used in Star Wars: The Empire Strikes Back.
- Thrawn wears a white colored version of Imperial Officer battle armor, first seen in the series on Wilhuff Tarkin.
- As of this episode, Kallus is now part of the Alliance to Restore the Republic.
- This is the first season finale in which Darth Vader and Ahsoka Tano don't appear.
- This is also the first finale in which the Inquisitors don't appear.
- This is the first time that The Bendu displays his force abilities besides vanishing into thin air instantaneously.
- Kiri Hart was one of the producers for this episode.