Barry faces Savitar and says that he knows who he is.
16 Hours Earlier
Joe and Cecile return to the West house after a marathon, They kiss and Cecile casually says that she love him. She apologizes and Joe takes a call from Barry. He tells Cecile that he has to head out.
At the lab, Barry tells the others what he's learned about physicist Tracy Brand. She's the key to stopping Savitar because in four years, Tracy will invent the technology that will trap Savitar in the Speed Force. They start tracking her down, and Julian wonders why they're not looking for the transformed Caitlin. He figures that they should stop her from teaming up with Savitar, and complains that no one is doing a thing. Cisco points out that they're working 24/7 to find her, and says that Julian shouldn't have ripped off the necklace and let her transform.
Cisco gets a hit on Tracy, currently a grad student. He, H.R., and Barry go to the university and Barry smells something burning in the lab. They go in with a fire extinguisher and Tracy complains, explaining that she's burning her work. Tracy says that none of her work works, and explains that she failed her dissertation. She's heading to Big Belly Burger to get a job, and explains that that her professor said it was a waste of time. H.R. tells her not to waste her mind making "finger chips," and Barry recites her future work. Tracy points out that she hasn't shred her work with anyone yet.
Killer Frost bursts in and fires a cold blast at Tracy. Barry moves Tracy out of the way, has H.R. get Tracy out of the way, and the next ice blasts sends him flying. Cisco prepares to vibe her, but Killer Frost blasts him back as well. Barry lights a Bunsen burner to drive her off and makes sure Cisco is okay. By the time they get out to the hallway, Killer Frost is gone and they realize that she's working with Savitar.
At the police station, Tracy works with a sketch artist to work up a picture of Killer Frost. Joe takes it to put out an APB, and talks to Barry privately. Barry admits that he didn't think that Killer Frost and Savitar would team up so soon, just as Cecile comes in and asks what they're talking about. Joe says that there's was a meta attack at the university, and asks to talk to Joe privately. Cecile asks if they're good after what she said, and Joe assures her that they're fine. Once the DA leaves, Barry asks Joe if he wants to talk. Joe doesn't, and Tracy prepares to leave. Barry suggests that she stay with Joe, and Joe agrees. Tracy insists that it was just a random attack and leaves, and Joe and Barry figure that they need to keep an eye on her.
That night, Killer Frost tells Savitar that Tracy escaped. He asks if Caitlin is still inside of her, undermining her intentions, and points out that Killer Frost hasn't killed anyone yet. Savitar tells her to kill the woman so that they can be gods.
H.R. finds Tracy at Jitters bus station and buys a coffee for her. She recognizes him and wonders if the GCPD sent him to check on her. H.R. says that he and his team are interested in her work, and Cisco briefs him over the earbud, reciting the details. Julian wonders if H.R. is trying to flirt with Tracy, and points out that he saw Cisco and Killer Frost on the security footage that they wiped to protect her identity. He notes that Cisco had a clear shot and didn't take it. Cisco refuses to discuss it, and checks in with Barry and Joe outside running surveillance. Joe finally admits that Cecile caught him off-guard and he didn't think they were "there" yet. He doesn't figure that it's the right time to get involved with someone that he'd have to lie to, and Barry advises him to tell Cecile the truth.
Tracy and H.R. grab a table and she explains that she's been studying speedsters. She thinks the trail that they leave comes from sort of dimension. H.R. suggests the name "Speed Force," and Tracy suggests that she might have a way to control it. the university wouldn't fund he research, and she wonders why H.R. is so interested in it. H.R. assures her that she's no crackpot, just as his coffee freezes solid. He gets her outside and calls for help, just as Killer Frost fires an icicle at Tracy.
Flash speeds in and catches it, and Killer Frost steps forward. H.R. gets Tracy away, and Killer Frost speeds off after Tracy on an ice ramp. Flash tells Cisco to knock her out when he lures her back, and speeds after her. Killer Frost stats blasting civilians to distract the pursuing Flash, and he manages to driver her back. Vibe prepares to knock her out, and Flash arrives and tells him to do it. Memories of his friend Caitlin go through his mind, and Killer Frost blasts the paralyzed vibe. Flash takes the blast meant for his friend and is knocked out. Killer Frost stabs Flash in the left leg to keep him from following her.
Later, H.R. takes Tracy to STAR Labs and they explain that Killer Frost is teamed up with Savitar and Tracy creates the technology to trap him. Tracy realizes that her theories about the Speed Force are correct, and shows her the holographic data file from 2024. Flash asks her to build the trap now, and they warn that if she doesn't then someone important to them will die. Tracy excuses herself and H.R. says that he'll go after her.
Later, Julian visits Cisco in his workshop and tells him that H.R. talked Tracy into helping them. He then asks Cisco why he couldn't attack Killer Frost. Cisco finally says that he's afraid of killing his best friend by accident, and that he'd rather die than do that.
Barry talks to Joe and asks if he's told Cecile about them. Joe explains that Cecile is the only normal thing in his life, and if he tells her about them then it goes away. Barry says that there's no such thing as normal, and love is the only thing that will get them through it. H.R. runs in and says that Tracy is gone.
Barry speeds to all of Tracy's potential locations but doesn't find her. H.R. figures that she's okay and something happened to her, and suggests that they check the data file. They find photos of her at a park and H.R. realizes where she is.
H.R. approaches Tracy, sitting in the park looking at a statue of Galileo. He's brought her a coffee, and she apologizes for running off. Tracy explains that she used to find the fact that people thought Galileo was a crackpot comforting because people think the same of her. She admits that she was unnerved by everything she saw in the data file, and figures that H.R. is a genius. H.R. admits that he isn't but assures her that she can defeat Savitar if she believe sin herself. He tells her that for what it's worth, he already does.
Joe is at home when Cecile comes by. She wonders what's going on, Joe says that he's worried that things will change, and what she said showed him where he was in their relationship. He suggests that they should stop seeing each other, and a shocked Cecile tells him that she thought being together was the best thing for both of them. Cecile says that she'll see him around the station and leaves. However, there's a knock on the door seconds later. Killer Frost is there, holding an ice dagger to Cecile's throat. Killer frost tells her to bring Tracy to the address she'll give him in an hour, or she'll kill Cecile. When Joe tries to go after her, Killer Frost blasts him down and leaves.
At STAR Labs, Joe tells the others what happened. Julian refuses to let Killer Frost kill someone, and Barry insists that no one will die. Killer Frost texts the address, at an old factory, and Barry says that he has a plan.
As Cisco heads down the hallway, Julian approaches him and tells Cisco that he can control his power. He figures that Cisco's powers come from love, and if Cisco can stop Killer Frost then they can save her.
Tracy is working in the lab when H.R. comes in and asks her to do something dangerous.
At the factory, Cecile is tied up to a chair. Joe, Flash, and Tracy arrive and Killer Frost steps out to say that she intends to kill Tracy. Flash says that Savitar is just a man that is using Killer Frost, and she echoes his words about how they protect each other. She explains that Savitar told her everything that Flash would say, and that's why Savitar is always one step ahead of them. Killer Frost knows that Vibe is in the rafters, and triggers a bomb there. He creates a breach to break his fall, and Killer Frost freezes Joe's gun. Flash takes the blast meant for Tracy, and Killer Frost freezes him to the floor. However, Vibe blasts her down and says that it's over. Killer Frost gets up and goes after him, and the two of them match their powers against each other. He manages to push past her resistance and knock her out, just as Flash breaks free. Vibe runs to Killer Frost and takes a blood sample from her.
Savitar speeds in, knocking Vibe down, and says that his ascension is nearly at time. He tells Flash that as he rises, Flash will fall, picks up Killer Frost, and speeds off.
Back at STAR Labs, Cisco realizes that Savitar knows precisely what is going on, as if Savitar was there. Iris wonders why Savitar rescued Killer Frost instead of killing Cisco. Julian examines the blood sample and says that it could be the cure to reverse-engineering a cure.
H.R finds Tracy examining the shard from Savitar's armor. He says that he wants to make sure that she doesn't get hurt, and Tracy says that she thinks that Savitar's armor is made out of "strange metal." He needs the suit to negate the energy he builds up when speeding, and figures that if they can create a device to harness the power and use it against Savitar to trap him in the Speed Force. H.R. figures that she's a genius and will stay with them, and that his future is changing.
Joe asks Cecile to see him in his office. He tells her that he froze when she said that she loved him, and warns that his love comes with a lot of baggage. Joe tells her that he's done with the self-doubt and says that he loves her with all of his heart. He apologizes for being dishonest with her, and promises that there will be no secrets between them. They kiss and then Joe tells her about the speedsters in his life.
Later, Joe returns home and finds Barry, Wally, and Iris waiting for him. he says that he told Cecile everything, and she promised not to tell anyone. Joe tells them that love made the difference, and Barry gets an idea as he remembers everything he's seen of how Savitar has always been one step ahead of them, and Julian/Savitar saying that he is the future Flash.
Flash speeds off to a street and yells to Savitar that he's there. Savitar arrives and Flash tells him that he knows who he is. He figures that everything about Savitar is about time, and he knows everything about all of them. Barry figures that Savitar knows how to use their love against them, and they can't stop him because he was there: he lived it when he was Barry. Savitar removes his armor to reveal that he's a future Barry.
Written by Gadfly on May 3, 2017