"Nightsisters" is the twelfth episode of the Star Wars: The Clone Wars television series' third season. It aired on January 7, 2011. The episode chronologically succeeds Senate Murders and precedes the next episode, Monster.
"Troubled by Asajj Ventress' growing prowess with the dark side of the Force, Darth Sidious commands Count Dooku to eliminate her. But Ventress survives Dooku's assassination attempt, and the jilted former apprentice vows to take revenge, enlisting the aid of her kinswomen -- the mystical Nightsisters -- in her sinister scheme.
Mother Talzin, leader of the Nightsisters, veils Asajj and her fellow assassins in a cloak of invisibility, and they infiltrate Dooku's palace on Serenno. Though they fail to kill the Count, their use of captured Jedi lightsabers leads Dooku to mistakenly believe that the Jedi have tried to kill him. Interested in protection, he requests a new apprentice from Mother Talzin."
Asajj Ventress leads a space battle against Republic forces commanded by Jedi General Anakin Skywalker and Obi-Wan Kenobi in the Sullust system. Ventress singles out Kenobi and attacks him, damaging his fighter, whereupon she is in turn knocked unconscious by Skywalker. Both combatants crash in the hangar of the Separatist flagship.
Meanwhile, however, a conspiracy is brooding against Ventress' life. Darth Sidious confers with Count Dooku, expressing his concerns about Ventress' growing power, and orders his disciple to destroy her before she becomes too strong to handle, and Dooku, under the will of his master and to afraid to protest, is reluctantly forced to obey. When Ventress calls him for assistance, he abandons her for her supposed failure. Shaken and infuriated, Ventress viciously engages Anakin and Obi-Wan in lightsaber combat. The confrontation is interrupted by Dooku's order to have the flagship bombarded by the other Confederate ships to ensure her destruction; the combatants barely escape with their lives. Dooku then informs Sidious of Ventress' supposed demise. The Dark Lord is satisfied that Dooku's loyalty to him is intact.
Ventress is left floating in space in her nearly destroyed fighter until she is recovered by a scavenging crew, who intend to ransom her to her employers. Instead, they are all killed by Ventress, who commandeers their vessel and proceeds to the location of her old order, the Nightsisters, where Clan Mother Talzin has her tended to. In her feverish dreams, Ventress recalls how she was rescued from a slaver whom her mother sold her to and taken in by Jedi Knight Ky Narec as a child, her apprenticeship under him, his death and her descent into the dark Side, her being taken in by Dooku and his betrayal. Upon awakening, she swears an oath of revenge against her former master; Mother Talzin puts two of her finest warriors, Naa'leth and Karis, to assist her and provides her with the means of approaching and combating Dooku with the help of mystical invisibility potions and poisons.
The three Nightsisters travel and penetrate Castle Serenno on Serenno, where they catch him asleep. His senses dulled by Ventress' poison dart and the cloak of invisibility which surrounds his attackers, Dooku is caught at a disadvantage but fights back furiously, thinking his assassins are Jedi since Mother Talzin has armed Ventress' team with lightsabers. Nearly beaten, Dooku, who fakes being completely drained of energy, instead channels all of his rage, and, in one extremely powerful blast of Force lightning, he evicts them from his palace and disrupts their invisibility. Mother Talzin is content, however. With this attempt on his life, she reckons that Dooku will now be more anxious to get himself a new assassin and bodyguard to protect him. She contacts the Count and suggests a replacement—a male Zabrak warrior from her people—an offer Dooku decides to accept.
When Ventress is rescued from the wreckage of her starfighter, the long skirt of her outfit has disappeared.
- Star Wars: The Lightsaber Collection