We pick up our story in Tokyo, where Cass has beaten O-Ren Ishii and her bodyguards, the Crazy 88. An angry Batman flies in to scold her and drag her reluctantly back to Gotham City. Undaunted, Cass flees and after a brief night-time chase, eludes her mentor. She knows she's risking a complete break with the man who has rapidly become a second father to her, but she's driven by her need to pursue these unusual and deadly people who remind her so much of herself. Inside Cass rages a crisis of identity. Using her own resources, she slips back across the Pacific and into the U.S. only to meet...
California Mountain Snake (Elle Driver). California Mountain Snake briefly lulls Cass into a false sense of security by posing as an ally, but when the moment is right, strikes. What follows is another sword fight, but Cass has developed katana expertise beyond anything California Mountain Snake can handle. Cass ends the fight by temporarily blinding the one-eyed killer with a bright light, slipping behind her and shoving her into a filthy dumpster. She closes the top and uses a small metal torch from her utility belt to seal it shut. As Cass slips away, we hear California Mountain Snake raging and pounding away helplessly inside her dark prison.
Black Mamba/The Bride (Beatrix Kiddo). Following up on information gleaned from Cass's defeated foes, Oracle reveals to Batman the location of the comatose Black Mamba. Batman heads there hoping to intercept Cass who must also have access to this information. Sensing something sinister at the facility, and backtracking the patient's origins, Batman begins to piece together the puzzle of the Deadly Viper Assassination Squad. When Cass finally does show up, Batman realizes he must let her work through her issues. Grimly, he gives her approval to confront Bill himself. If she can find him. Because of the strain it's caused in their relationship, it's the most he's willing to do. Oracle chides him for testing the girl and Batman questions his own motives.
But not before Black Mamba recovers from her coma during a course of events that exactly follow those in Kill Bill Vol. 1. A freed California Mountain Snake makes her aborted attempt on Black Mamba's life. Black Mamba kills her tormentors and regains the ability to walk and fight. Cass confronts her before she heads off to wreak vengeance on the Deadly Vipers and Bill. Realizing Cass is after Bill as well, Black Mamba cannot allow her to defeat him before she takes her own shot. The two fight, a long, running battle that takes place over the rooftops near the hospital a la Crouching Tiger, Hidden Dragon, with Black Mamba pursuing Cass just as Shu Lien did Jen Yu. Both combatants believe the other knows where Bill is hiding. They're fairly evenly matched, with Cass holding a slight advantage. When the truth that neither knows where Bill is comes out, they stop their match and Black Mamba exacts an honor vow from Cass that they will meet again when it is all over and settle their differences once and for all, but that she must be the one who kills Bill. Cass is shocked because she had only thought of bringing Bill to justice for his crimes and once again, she sees a reflection of the self she could have been. In her confused state, she allows Black Mamba to slip away and experience the events of the Quentin Tarantino film. Deciding she has to redeem herself in Batman's eyes, Cass breaks the vow she's only just made and grimly follows Black Mamba from a distance.
Bill. Pursuing Black Mamba, Cass returns to many of the locations from the previous volume, only too late. She witnesses the carnage left in Black Mamba's wake, becoming increasingly distraught at what she feels resulted from her failure to stop her when she had the chance. She fears Batman will never forgive her for her lapse. It's a horrible nightmare trip for her, a dark journey through an underworld she might once have easily inhabited herself.
After encountering the maimed Sofie Fatale and learning Bill's whereabouts, and having a phone conversation with him-- one-sided, of course, because Cass can barely understand what he's saying-- where Bill attempts to work his own charms on her and bring her onto the Deadly Viper Assassination Squad as its newest recruit (using the same logic he employs on Beatrix Kiddo in the film), Cass has an epiphany and now knows she has to save Bill from Black Mamba even though she considers him a very bad person indeed.
Unfortunately, she's once again too late and can only helplessly watch Bill's final moments. Although she can't fully comprehend the feelings that pass between Black Mamba and Bill, she does know there are some things beyond her limited emotional experience. Now having learned the full story and what the Deadly Vipers did to Black Mamba when she was The Bride, Cass offers a truce. Seeing the now at peace Beatrix Kiddo reunited with her daughter sends Cass winging back to Gotham City to repair her relationship with Batman. And to begin her own search for her elusive mother. Of course the rigid Batman isn't too happy with her performance, but Oracle convinces him to back off for now. There are some things about Cass that are also mysteries to them.
Yeah, kind of anti-climactic, huh? Oh well, they can't all be winners.