Barry and Iris fight over him sending Nora back without consulting her. Iris reprograms the Time Sphere and travels to 2049. There, Nora wants Thawne to teach her how to use the Negative Speed Force to time travel without being detected by her father. After an unsuccessful attempt, Nora and Thawne are confronted by Iris, who wants to take Nora back with the Time Sphere. An upset Nora instead enters the Negative Speed Force. Thawne admits he made a mistake and tells Iris to reunite her family. Meanwhile, Icicle steals a cryo-atomizer from Tannhauser Industries and then kidnaps Caitlin and Carla, planning to eliminate their human sides. Caitlin turns into Killer Frost to fight Icicle, while Barry saves Carla from a cryo chamber. Icicle is about to kill Caitlin, when Thomas Snow suddenly finds the strength to return to his human form. Cicada, who earlier kidnapped her younger self, arrives and fights Killer Frost. Thomas sacrifices himself for his daughter by stepping in front of Cicada's dagger, after which Cicada escapes with the cryo-atomizer. Unknown to anyone, Carla tests positive for icicle powers. Finally, Barry admits he was wrong and he and Iris agree to work together to help their daughter. Elsewhere, Nora emerges from the Negative Speed Force with glowing red eyes.