After the nuclear explosion separates Ronnie (guest star Robbie Amell) and Dr. Stein (guest star Victor Garber), Barry (Grant Gustin) and the team believe both men are safe. Caitlin (Danielle Panabaker) is thrilled to have her fiancé back and prepares to resume their life together while Dr. Stein returns to his wife. However, when General Eiling (guest star Clancy Brown) targets Firestorm, Ronnie and Dr. Stein must decide if they are safer together or apart. Meanwhile, Mason Bridge (guest star Roger Hayworth) tells Iris (Candice Patton) that there is something secretive going on at S.T.A.R. Labs and Dr. Stein gives Barry some important information about time travel.