"Blood Sisters" marks the eighth installment of the second season of the animated television program Star Wars Rebels. In the overall series, it holds the position of the twenty-third episode. This episode was initially broadcasted on Disney XD on November 18, 2015.
On the surface of the planet Garel, Hera Syndulla dispatches Vaux along with a female companion to acquire fighter components from the local marketplace, coinciding with the arrival of Sabine Wren, Ezra Bridger, and Chopper. Syndulla assigns Wren a specific task: to locate a courier possessing highly confidential intelligence and safely transport him to Havoc Outpost. Syndulla emphasizes the critical nature of the information held by the courier, stressing the importance of its secure delivery. When Wren inquires about the courier's appearance, Syndulla admits to not knowing, but provides the code phrase "It's a long way to Alderaan," to which the courier will respond. With her instructions clear, Wren, accompanied by Bridger and Chopper as support, sets out to rendezvous with the courier. En route, Bridger comments to Wren about her perceived solitary nature, noting her preference for handling missions independently and her inclination towards solitude. During their conversation, Wren notices a marking painted on a nearby wall that appears familiar, causing her visible concern. She then rejoins Bridger and Chopper, and together they arrive at the designated hangar where they are to meet the courier. As passengers disembark from arriving shuttles, Wren and Bridger attempt the code phrase with each passing individual and civilian. However, no one responds, and some react with awkwardness and move away. As hours pass and the hangar prepares to close, Wren and Bridger remain unsuccessful in locating the courier. Eventually, they discover that the courier is actually an EG-series power droid known as EG-86, who arrived concealed within the cargo payload. They also realize that they are not the only ones seeking the courier, as another party is also in pursuit: a bounty hunter identified by Wren as Ketsu Onyo.
Bridger comes to understand that Wren and Onyo share a shared history, as Onyo was instrumental in Wren's escape from the Imperial Academy on Mandalore, after which they embarked on a career as bounty hunters. According to Wren, they initially aspired to join the notorious criminal organization called the Black Sun, but Onyo betrayed her out of greed, leaving her for dead while she herself ascended within the ranks of Black Sun. Onyo retorts that Wren would have been better off dead than aligning herself with the rebellion. She had doubted Wren's involvement until discovering that the Empire had placed a bounty on her head. Nevertheless, Onyo clarifies that she has no intention of claiming the bounty, as her primary objective is to secure the courier. Wren warns Onyo that she will not allow her to take him, but before their confrontation can escalate, they are interrupted by the arrival of stormtroopers. The stormtrooper leader informs them that the hangar is closing and orders them to depart. Onyo responds by opening fire, initiating a gunfight. As more troopers arrive, Bridger instructs Chopper to secure EG-86 aboard a nearby shuttle while he, Wren, and Onyo fend off the stormtroopers. Once the droids are safely on board, Bridger and Wren join them. Chopper disables the pilot droid, and Wren starts the engines. However, as they take off, Bridger is thrown overboard when a shot from one of the stormtroopers hits the shuttle door, causing him to lose his footing. As the shuttle departs, he contacts Syndulla and informs her that the mission has become "high profile." Meanwhile, the stormtroopers surround Onyo and hold her at gunpoint. After ordering her to drop her weapons, Onyo launches a surprise attack, swiftly incapacitating the troopers in close combat. She then makes her escape, using a departing shuttle as a platform to reach the roof where her ship, the Shadow Caster, awaits.
Wren and Chopper are now in space, and despite leaving Bridger behind, they continue with the mission to deliver EG-86 to the rendezvous point. Just before initiating the jump to hyperspace, they detect Onyo's ship approaching. She swiftly closes in from behind and unleashes a barrage of fire on the shuttle, disabling their hyperdrive. Wren anticipates Onyo's next move and instructs both droids to secure their feet. Onyo maneuvers the Shadow Caster alongside Wren's shuttle and blasts open the side door, creating a hull breach. Chopper is expelled into the vacuum of space, while EG-86 and Wren find themselves trapped in the doorway. With considerable effort, Wren manages to activate the force field, sealing the breach. Onyo positions the Shadow Caster directly in front of Wren's shuttle and establishes communication. She threatens to destroy the shuttle unless Wren surrenders the droid. Unbeknownst to her, Chopper, after briefly drifting in space, has managed to land on her ship and is sabotaging her weapons systems. Wren notices this and skillfully distracts Onyo, buying Chopper enough time to disable her main cannon. While Onyo expresses her pride in being associated with the Black Sun, Wren expresses only disdain for having once desired that life, recognizing that the Black Sun are ruthless slavers and assassins who prioritize only body counts and profits, even at the expense of their own members. After Wren again refuses to hand over the droid, Onyo reluctantly opens fire on her former friend, but thanks to Chopper, the guns are disabled. Wren bids her farewell and activates the thrusters on her shuttle, with Chopper in pursuit. Onyo then uses a tractor beam to capture him and hold him hostage. Wren reverses course and docks with the Shadow Caster, agreeing to a trade. Meeting face to face, Onyo realizes that Wren remains unwilling to relinquish the courier. Onyo offers to split the bounty with her if she hands over the droid, but Wren informs her that she is no longer motivated by profit, having joined the rebellion's fight against the Empire. Onyo expresses skepticism about the rebellion's ability to overthrow the Empire, deeming it a futile endeavor. In her view, survival is paramount, and trust is a luxury that cannot be afforded. Wren tells Onyo the rebellion gave her a second chance in life. Back when she was only out for herself, she met good people who helped her become more than what she used to be and fight for the right cause. She forgives Onyo for abandoning her and offers her a second chance. At that moment, they receive a transmission from an approaching Arquitens-class command cruiser that has been tracking the stolen shuttle, threatening to open fire if they attempt to escape. This situation compels Wren and Onyo to collaborate once more.
As the Imperial vessel draws closer, Wren devises a plan, instructing Chopper to overload the hyperdrive on the shuttle. She then contacts the Imperial vessel, warning them that their ships have sustained significant damage and are at risk of self-destruction. The Imperials conduct a scan and confirm Wren's assessment. The commanding officer grants them two minutes to stabilize the situation before initiating docking procedures. Onyo begins to grasp Wren's strategy. She intends to destroy the shuttle, providing them with the time needed to escape. Utilizing explosives stored on the Shadow Caster, Wren strategically places them throughout the shuttle, preparing for detonation. She then reactivates the pilot droid and instructs him to activate the emergency protocols before retreating to the Shadow Caster. The Imperials detect the shuttle powering up and begin to open fire. They strike the docking tube, and Wren is knocked unconscious by the resulting blast. Onyo prepares to flee, but the droids refuse to abandon Wren. Overwhelmed, Onyo rescues Wren as the shuttle attempts to break free from the docking with the Shadow Caster. Finally, everyone is safely aboard, and the Shadow Caster detaches from the shuttle, but both ships are ensnared in the Imperial cruiser's tractor beam. The explosives on board the shuttle then detonate, obliterating the shuttle and inflicting severe damage on the Imperial cruiser. The Shadow Caster, now free of the tractor beam, escapes into hyperspace.
Wren, Onyo, and Chopper arrive at Havoc Outpost to deliver EG-86 into safe custody. They are greeted by several Alderaanian rebels, including the astromech droid R2-D2. Subsequently, they return to Garel and land, where Syndulla and Bridger await their arrival. Syndulla commends Wren on the successful completion of the mission and expresses gratitude to Onyo for her assistance. Before parting ways, Wren thanks Onyo for saving her life and extends an invitation to join the rebellion should she ever consider it. After shaking hands, Onyo boards her ship and departs as Wren and Bridger observe.