Season 04, Episode 09 – “Don’t Run”
Amunet kidnaps Caitlin and puts meta-dampener handcuffs on her to keep her from turning into Killer Frost. Amunet tells Caitlin she needs her to perform a tricky medical task and if Caitlin fails, Amunet will kill her. Meanwhile, the Thinker traps the Flash in a speedster-proof prison. With the clock ticking, the team doesn’t have the time or resources to track both Caitlin and Barry, so Iris is forced to choose who to save.