Barry and Iris go on a vacation to an island in the Indian Ocean.

Joe believes that Kristen Kramer was behind an ambush at Fort Dakota years ago. They never caught the bomber.

Allegra gets an anonymous tip from the Citizen about where Ultraviolet is. She believes that her cousin is coming to Central City to assassinate someone.

Esperanza, AKA Ultraviolet, shows up at CC Jitters and attacks Allegra and Chester. Sue arrives just as the police arrive. Esperanza vanishes.

Team Flash, consisting of Caitlin, Chester, Allegra, and Sue, work together to find Esperanza's next location. There, Esperanza tries to kill a doctor. Allegra and Sue stop her with a photonic stun grenade and let the doctor getaway.

Esperanza tells them that she wasn't hired to kill the doctor -- Dr. Olsen. She wanted to kill him because he created her.

They take Esperanza back to S.T.A.R. Labs. Allegra promises Esperanza that they will take down Dr. Olsen together.

At the CCPD, Joe confronts Kristen about the Fort Dakota mission. She kicks him out of her office.

Esperanza trains Allegra to control her powers. Sue arrives and fights Esperanza. Chester accidentally gets hit by one of Ultraviolet's blasts. Esperanza leaves to take down Dr. Olsen herself.

Caitlin patches up Chester. Allegra apologizes to him.

Kristen texts Joe asking him to meet up with her.

Sue tells Allegra that her parents were too far gone to save after being with Black Hole for so long.

Chester figures out how to track Ultraviolet by using Allegra as an input signal. They find her at a run-down warehouse. There, Esperanza, under the influence of Dr. Olsen, attacks Allegra. He has ordered her to kill Allegra, Sue, and Chester.

Allegra overpowers Esperanza and stops Dr. Olsen.

Esperanza recovers at S.T.A.R. Labs. Dr. Olsen goes to jail.

Caitlin believes that she can use Dr. Olsen's files on Esperanza to cure her.

Kristen tells Joe that the soldier who betrayed her unit -- Adam Kreyke -- was like her brother. She had no idea that he sold out her unit. Kristen has been looking for Adam for six years. Now, she wants Joe to help her catch him.

Allegra asks Chester out for coffee, but he has a D&D game set up. She asks if she can join him, and he says yes.

Barry returns.

Frost finds Chillblaine, who has broken out of Iron Heights. He tells her that he turned state's witness.