As Eva becomes more powerful, Barry and the team must find a way to stop her; an old friend risks her life to help.
After Black Hole hires Rag Doll to kill Joe, Singh suggests that Joe go into the witness protection program; Ralph runs into Sue; Iris becomes suspicious of Eva.
Feeling overwhelmed with all the changes since Crisis, Barry conducts an experiment that goes awry and puts him directly in Gorilla Grodd's path; Iris works with Eva to escape the Mirrorverse.
After recent events, Barry takes a closer look at his life with Iris. Meanwhile, Eva makes a bold move.
When Barry suddenly gains the power of speed thinking, he attempts to use his new gift to save Iris. While Barry is thrilled with his new power, Cisco is hesitant to trust it. Meanwhile, Eva must face a shattering truth.