In a new clip from "Running to Stand Still," the midseason finale of "The Flash," Iris (Candice Patton) tells Joe about the son Francine had after she left them. When Joe learns about Wally, his reaction is immediate -- and it looks as though it breaks Iris' heart to watch.

Starring Grant Gustin, Carlos Valdes and Jesse L. Martin, "The Flash" airs Tuesdays at 8 pm EST on The CW.