Killer Frost


 * For the eponymous characters, see Killer Frost (disambiguation).

"Killer Frost" is the seventh episode of the third season of The Flash, and the fifty-third episode overall. It aired on November 22, 2016. It saw Caitlin almost lose control and become a copy of her Earth-Two self.

Synopsis
Caitlin uses her powers to save Barry but as her mother predicted, the effort unleashes her inner Killer Frost. Killer Frost goes on a rampage looking for Dr. Alchemy, kidnapping Julian and battling both The Flash and Vibe. Meanwhile, Joe and H.R. have a heart to heart talk.

Plot
With Barry's life threatened by Savitar, Cisco and Caitlin are convinced by H.R. to go help him with their powers. Cisco takes them to Barry through a breach, giving himself a bad migraine in the process. On Barry's command, Caitlin releases a blast of her powers, momentarily making Savitar visible to them as he freezes. However, the evil speedster breaks loose and runs away. Back at S.T.A.R. Labs, Caitlin gives Cisco something for his headache, telling him he will be fine with some rest.

Caitlin later goes to the Central City Police Department, where she finds Joe West in the interrogation room interrogating a follower of Alchemy, Caitlin knocks on the door interrupting the interrogation, she then tells Joe that Wally is okay which prompts Joe to leave. Caitlin enters the Interrogation room where she then freezes the camera and by doing this causes her hair to partly turn white as a side effect of her powers. Caitlin then asks the Follower of Alchemy as to Alchemy's whereabouts, she does not get the answer she seeks and lashes out which bringing attention of nearby police, Caitlin then breaths cold air into the room which creates a mist and she leaves under the cover of her mist and freezes the door locking the policemen inside. Julian witnesses Caitlin leaving the room and because of this Caitlin takes Julian hostage, she then takes him to a freezer warehouse, where she tells him to work on a search for Dr. Alchemy; however, as the terms are common, she changes the search to Savitar.

Upon hearing about a cryokenetic meta kidnapping Julian, Barry and Cisco realize Caitlin has finally lost it. They find her using a scanner normally used for the Cold Gun. As the Flash, Barry knocks out Julian and learns Caitlin wants to find Alchemy to get rid of her powers, blaming Barry for causing her to turn into a cold-hearted killer. The police arrive, forcing Barry to get Caitlin out of sight; she severs one of his leg muscles, telling him not to follow.

A few hours later, Barry heals, deciding to pay Julian a visit to keep Caitlin from getting arrested. He promises to not to tell Singh, so long as Barry resigns; Julian also tells him about the Savitar search Caitlin had him do.

Barry informs the rest of the team about Caitlin's plan, deciding to have himself and Cisco watch one of the Acolytes, while H.R. and Joe watch the second. H.R. tells Joe during their stakeout that he should trust his gut when it comes to Wally. Caitlin attacks the Acolyte Barry and Cisco were watching, learning that he was told by Savitar that she is destined to become the insane Killer Frost. Barry and Cisco fight Cailtlin, who almost kills Barry with a freezing kiss. Cisco knocks her out, allowing Barry to thaw himself out.

Taking Caitlin to the Pipeline, Barry and Cisco learn Joe made the dumb move of getting Wally out of the caccoon too soon, leaving his brain unstable. Needing the old Caitlin back, Barry forces her to try killing him to escape; however, her true compassionate self reasserts itself, allowing Caitlin to rejoin the team. She devises a serum to heal Wally's brain, bringing him back to his senses.

Back at the hospital, Julian hears Savitar's voice, leading him back to the C.C.P.D. where he pulls out the mask of Dr. Alchemy.

Trivia

 * The fight between Caitlin and Cisco is similar to what he vibed when she asked him to see her future. There is only one minor difference; in his vibe, she was completely Killer Frost, and he was wearing the full Vibe suit.
 * The episode title was inadvertently revealed by director Kevin Smith himself when he posted an image of the script to his Twitter account. Although he'd covered the title on the front page with a pen, the paper was thin enough to clearly see the episode title printed on the second page of the script.
 * Greg Grunberg and Kevin Smith both serve as co-hosts for the AMC late night talk show comedy Geeking Out.
 * After thoroughly beating Barry, Savitar asks him if he has had enough, and Barry replies, "not even close." This is the same line used in episode twelve of season two, "Fast Lane", where Harry asked if Zoom's had enough after injecting himself with some of Barry's Speed Force energy, and he replies, "not even close."
 * When Joe is told to go and help H. R. on the stakeout, the latter describes it as an "all-star team up." which is also the name of the eighteenth episode of season one, "All Star Team Up".
 * The confrontation between Savitar and Barry bears a striking conceptual resemblance to that between Zoom and Barry in the Season two episode "Enter Zoom": In both cases, a superb speedster reveals a yet unrivalled level of power and is eventually subdued for a short moment before escaping the scene.
 * Cisco tells Caitlin that she gone all "mother of dragons" because of her white hair, referenced to Daenerys Targaryan from Game of Thrones.
 * Wally becomes a speedster in this episode.