The Flash gets an assist from XS. Meanwhile, CCPD enlists Chester for help when a mysterious device is found at a crime scene.

Barry’s desire to keep Team Flash safe is tested when Frost recklessly courts danger as she tries to stop the “Black Flame,” meanwhile, Iris tries to help a teen girl…

Kara investigates a secretive new group whose leader, Thomas Coville, has a mysterious connection to Supergirl. Meanwhile, Samantha feels like she’s letting Ruby down, and J’onn confesses an old secret.