As Iris receives word of a career milestone, Barry is suddenly nowhere to be found. In trying to get back home, Barry runs across many familiar faces. Khione continues to figure out her powers, and Chester works on a suit for Allegra.

Iris is alarmed by Barry's disappearance and Cecile assures her everything will be ok, but does she know that for certain? Team Flash is affected by a mysterious substance and Khione develops a better understanding of what she can and cannot control.