Star Wars Rebels has a banner installment in Secret Cargo. A critical piece of the rebellion falls into place. We are finally introduced to Senator Mon Mothma (Genevieve O'Reilly), an important character in the lexicon. She becomes a primary leader. In the case of the non-canon books, the republic chancellor after Palpatine's death. Who doesn't remember her famous "many Bothans died" line in Return of the Jedi?
Secret Cargo opens with the Ghost waiting in the wreckage of an old trade federation ship. Hera (Vanessa Marshall), Zeb (Steve Blum), Ezra (Taylor Gray) and Chopper are on a top secret rendezvous. They are to refuel a highly classified transport. They watch the Imperial Holo-Net. Senator Mon Mothma has been branded a traitor. She openly challenged the Emperor on the senate floor. Calling him a killer and the true enemy of peace in the galaxy. Ezra is impressed by her courage.
An imperial probe droid drops out of hyperspace. It scans the wreckage. Hera powers down the Ghost. Then tells Ezra to man the lasers. The droid swoops in and detects their life signs. Hera fires up the ship in pursuit. Ezra destroys it as the rebellion ships arrive, several Y-Wings and the transport ship. They dock with the Ghost to refuel.
The Gold Wing squadron leader is Captain Vander (Yuri Lowenthal). He tells them that they must refuel quickly. It would have been smarter to have avoided the probe droid. It must have sent a signal back. The Gold Two pilot (Mary Elizabeth McGlynn) also gives them heat for their destructive, high-profile antics. The Ghost crew takes umbrage at this criticism.
Imperial ships appear on the scene. They open fire on the rebel ships. Gold Two is knocked out as the Ghost is hit. Vander and Ezra jump into the Y-Wings, detach, and return fire. It's too late as the transport ship has taken too much fire. Hera races to undock the Ghost and take the crew of the other ship. The blast door opens; the secret passenger is Mon Mothma herself.
Ezra and Vander destroy the attacking TIE Fighters. It gives everyone time to jump to lightspeed. On the Ghost, Mon Mothma tells them the vital mission. She is on her way to Dantooine. There she will meet with the other factions of the rebels. She has issued a call to unite and consolidate all forces. Mon Mothma makes a cup of tea for Hera. She tells her that she can she no longer stay out of the fight. The only action left is to fight the Empire.
Meanwhile on Lothal, Grand Admiral Thrawn (Lars Mikklesen), Admiral Pryce (Mary Elizabeth McGlynn) and Admiral Konstantine (Dee Bradley Baker) review the battle. Thrawn deduces that it must have been Mon Mothma. They have the rebels surrounded, but he knows Hera's skill as a pilot and smuggler. He correctly assumes that Hera will try to go through a dangerous nebula to escape. Pryce begs him for the honor of catching the senator. Thrawn dispatches her to wait outside the nebula as they flush out the rebels.
The Imperial Star Destroyers are too big to give chase through the Nebula. Thrawn launches his armored, prototype TIE Fighter. The Ghost and the Y-Wings are about to enter the nebula. The TIE Defender, flown by Vult Skerris (Mario Vernazza) leads a squadron against the rebels. The Ghost and the Y-Wings enter the nebula under hot pursuit.
Gold Five sacrifices herself to prevent the Ghost from being destroyed. Hera decides to tempt fate. She orders everyone to put their forward shields at maximum. They veer dangerously close to a forming star. All the ships begin to overheat. Several TIE Fighters explode. The TIE Defender has to pull up to escape. The Y-Wings follow him to give the Ghost a chance. Hera plows ahead and escapes the Nebula, right into Admiral Pryce's Destroyers.
Ezra and Vander are in a pitch dogfight with the highly skilled Verris. Ezra begs Vander to trust him. He will loop around and bring Verris right into his sights. The tactic works as Vander hits Verris dead on, disabling his ship. Outside the Nebula, Pryce demands Mon Mothma surrender or be killed. Mon Mothma negotiates for time as Chopper readies the hyperdrive. It's too late as they are caught in Pryce's tractor beam.
Ezra and Vander come out of the nebula. They see the Ghost is almost captured. Hera orders them to hit the nebula gas with their photon torpedoes. It ignites a giant fireball that consumes the Star Destroyers. The Ghost and the Y-Wings jump to hyperspace when the tractor beam collapses. Vander and the recovering Gold Two shower the Ghost crew with praise. That was the best flying they had ever seen.
The Ghost arrives above Dantooine. Mon Mothma is projected into the Holo-Net by Chopper. She delivers an impassioned speech in support of the rebellion. Across the galaxy, her message is seen. At first there is no response at Dantooine. The Ghost waits in silence, suddenly dozens of ships drop out of hyperspace. The rebel factions have heeded her call. Star Wars Rebels continues the build up to the climactic appearance of Obi Wan Kenobi, on Disney XD.