Caitlin (Danielle Panabaker) uses her powers to save Barry (Grant Gustin) but as her mother predicted, the effort unleashes her inner Killer Frost. Killer Frost goes on a rampage looking for Dr. Alchemy, kidnapping Julian (Tom Felton) and battling both The Flash and Vibe (Carlos Valdes). Meanwhile, Joe (Jesse L. Martin) and H.R. (Tom Cavanagh) have a heart to heart talk.
Kevin Smith directed the episode with story by Judalina Neira and teleplay by Andrew Kreisberg & Brooke Roberts.