The CW’s The Flash introduced a new female speedster on season two episode 16 but she wasn’t in town to help out Barry. No, this speedster was all about using her speed to cause havoc while allowing everyone to believe it was The Flash who had turned to the dark side. Airing on March 22, 2016 and titled ‘Trajectory,’ episode 16 found Team Flash allowing themselves to have a night off of work and confirmed Cisco will never win a dance contest. The episode also contained a huge reveal and set in motion key events that will play out over the remainder of the season.
Barry (Grant Gustin) and Cisco (Carlos Valdes) stand on a cliff overlooking a river, with Dr. Harrison Wells (Tom Cavanagh) telling Barry he has to go faster than ever before in order to leap over the water and make it to the other side. Cisco attempts to give him the odds but can’t stop himself from continuously lowering them and Caitlin (Danielle Panabaker) telling him he shouldn’t do it if he doesn’t feel ready. But despite their misgivings, Barry’s certain he needs to keep pushing himself in order to make it back to Earth-2. Barry speeds across the gap and almost makes it to the other side before plummeting toward the water. Fortunately, Cisco was smart enough to bring along some drones and a net to rescue Barry before he can hurt himself or die.
Back at S.T.A.R. Labs, Jesse (Violett Beane) is munching on popcorn when the gang returns from Barry’s unsuccessful canyon leap. Team Flash has been working on Barry’s speed problem non-stop for a week, and now everyone but Barry thinks they need a break. Cisco comes up with the idea of going out to a club and even Caitlin is up for a night out. Jesse wants to go but her dad says no because he’s worried about her safety. Finally after much whining, Harrison gives in as long as she takes protection (a metahuman alert bracelet).
Barry, Cisco, Caitlin and Jesse order up drinks, toasting Jay when Iris (Candice Patton) and Wally (Keiynan Lonsdale) show up to join the fun. Jesse and Wally introduce themselves and the chemistry is definitely there, but Jesse’s bracelet keeps beeping. Cisco and Caitlin hit the dance floor and Jesse heads to the bathroom to take apart the bracelet, activating a recording stored on the bracelet of her father saying he would do anything to get her back, even kill. Meanwhile, Barry and Iris do a little flirting while talking about their marriage on Earth-2. And then the fun is broken up by a speedster who races through the club and steals wallets, purses, and everything from the cash registers. The Flash chases after her but she’s able to speed away before he can stop her.
Joe’s investigating the robbery and is amazed Barry wasn’t able to catch this mysterious unknown speedster. Barry’s worried people will think The Flash is a petty thief.
At Iris’ newspaper, editor Scott Evans (Tone Bell) wants the staff to work on stories that claim The Flash is in fact the robber and that he’s gone rogue. Iris says The Flash is a hero and there’s no reason why he would have done this for a few hundred dollars, but her questions fall on deaf ears. She’s forced to work on the story because she was there and witnessed it first-hand.
At S.T.A.R. Labs, Jesse confronts her dad about the recording. Harrison says it was either The Flash or her, and he’d do anything not to lose her. Jesse gets upset, calls him a killer, and leaves the room.
Barry and Cisco try to figure out how this unknown person became a speedster without them knowing it, and Caitlin shows them Velocity-9. Wells admits he and Caitlin worked on it and Barry’s upset they didn’t tell him about it so he could use it to take down Zoom and save Jay. Caitlin says Jay took it because he was sick to regain his speed and the formula is temporary and deadly. Cisco touches Caitlin’s shoulder because she’s crying and vibes, seeing Zoom. Before he can explain what he saw, he gets an alert that ‘Bad Flash’ is back. The Flash races off but is no match for this new speedster who it turns out is female.
At S.T.A.R. Labs, Cisco is excited they finally have a lady speedster. He wants to know if she was good looking, and Barry says next time she punches him in the face he’ll find out. Barry mentions she has a great suit and they determine that means it was made by someone who has access to the tech and a lab. Caitlin figures out it could have been a friend she consulted at Mercury Labs when she was working on the Velocity-9 formula.
Caitlin and Joe (Jesse L. Martin) go visit Caitlin’s friend and former co-worker Eliza Harmon (Allison Paige) at Mercury Labs, and Caitlin asks her if she’s heard about the bad speedster. Eliza thinks it’s The Flash but Joe says they know it was someone else. “Wow, how very law and order of you, Caitlin,” says Eliza, with the writers inserting a neat little reference to actor Jesse L. Martin’s former series, Law & Order. Caitlin asks about the time she worked on the formula, telling her it was somehow involved. Eliza says the research wasn’t stolen at her lab, assuring Caitlin she destroyed her research.
Back at the newspaper, Iris tells her editor she has a source who knows The Flash is not the speedster who’s been robbing people. When she won’t give up her source, she suggests they go grab some coffee to talk it over.
And meanwhile at Mercury Labs, Eliza is talking to herself about all the pressure she’s under. It seems Eliza is hooked on Velocity-9 and becomes a speedster to blow off steam. She injects herself and her eyes flash yellow.
At S.T.A.R. Labs, Barry’s still confused as to why he shouldn’t be taking the V-9 to make himself faster. He wants to be fast enough to stop Zoom and any speedster, and if it means cheating to make himself faster then so be it. But Harrison tells him, “Want to take a shortcut? Remember this: you lose a chunk of humanity every time you compromise your values.” Harrison tells him to be like Jay and Barry drops the vial of V-9 on the floor, shattering it.
Team Flash is talking about the speedster when she shows up and puts Barry in a cell, telling him it’s time she had some fun. Before his friends can help him, she pulls a gun on Harrison and asks for the V-9, calling herself Trajectory but Caitlin knows it’s Eliza. Caitlin tries to tell Trajectory it will make her very sick and could even kill her. She threatens Cisco and he hides behind the stand with Jay’s Flash helmet, touching it and again seeing Zoom during a vibe. Caitlin tells her the vials are all gone but Eliza doesn’t believe her. She pulls a gun on Jesse and Harrison says they’ll make a vial for her because they have all of the ingredients.
At CC Jitter, editor Scott and Iris get their coffee and discuss The Flash. Scott says everyone wants a hero and it’s their job to make sure even heroes are held accountable for their actions. Then things turn awkward when he assumes it’s a date which Iris didn’t mean for it to be.
Harrison gives Eliza the vials and tells her to let Jesse go. Eliza tests it by injecting Jesse with V-9 before speeding off. They free Barry and try to help Jesse who is now having a seizure. In order to save her, they have to get the drug out of her system by giving her a blood transfusion. Fortunately, Harrison’s a match.
Harrison’s by her bed when she wakes up while they’re still hooked up together. He apologizes for his actions and she asks how many more terrible things he’s going to do to protect her. She reminds him he didn’t even hesitate to give the crazy speedster what she wanted, and Harrison says it’s his job to keep her safe no matter what.
Caitlin tells the gang she put a micro-tracker in the drug and they track Eliza to the Central City Bridge. She’s running back and forth which will destroy the bridge and kill the people on it. Barry makes it to the bridge as pieces are falling off and 200 people are still on it. He collects them one by one, taking them all safety before facing off with Trajectory. As the bridge breaks apart in the middle, Trajectory races away and Barry will only be able to get to her if he makes the jump across the chasm, but he’d have to go mach 3.3 to do it. He thinks he can do it, gets into his runner’s stance, and launches himself off the broken edge of the bridge, landing on the other side and knocking Trajectory to the ground. He tells her it’s over and she goes to inject herself again. Barry tells her to stop and that he knows what she’s feeling. He tells her the V-9 is killing her, but she goes ahead with the injection anyway. She asks him how it feels to know she’s faster than he’ll ever be and races off, but the lightning behind her is turning blue. As she runs she starts to come apart until there’s nothing left but her clothing and mask.
Scott praises Iris for her article titled “Flash stops evil female speedster,” and she tells him not every hero is a fraud. She apologizes for misreading the situation and that him assuming it was a date surprised her. But she adds that once the surprise went away, it wasn’t a deal breaker. They smile at each other, and she leaves.
Harrison’s looking for Jesse at S.T.A.R. Labs and finds her bracelet. She recorded a message telling him that it’s her turn to go out into this new world and find out what it can offer. As she speaks, we see her get on a bus to Opal City.
Team Flash stands around talking about Eliza basically evaporating and Joe says at least now they know why Jay said it was so dangerous. Harrison walks in but doesn’t tell them Jesse is gone. Barry’s still puzzled about the blue lightning and they figure out that the V-9 is what turned the lightning that color. Zoom’s lightning is blue which means he’s dying from the drug, and Harrison figures out that’s why he wants Barry’s speed. It would be the cure. And Barry says, “Same as Jay.” Caitlin doesn’t want to believe it and Cisco says Zoom killed Jay in front of them, but Barry reminds the gang they’ve seen a speedster be in two places at once before. Harrison says there’s one way to find out and Cisco finally reveals that he’s been vibing Zoom, first when they closed the last breach and every time since it’s happened when he’s been near Jay’s helmet. Barry smashes the case and hands it to Cisco. Cisco holds the helmet and vibes Zoom again but this time he takes off his mask and it is definitely Jay. Barry races off, ending up at the edge of the cliff from the beginning of the episode where he lets out a tremendous scream.