As Zoom pulverizes Central City with an army of Earth-2 meta-humans, Barry's team (including newly returned Caitlin) worries that Barry's experience in the Speed Force has left him feeling recklessly invincible, Caitlin experiences PTSD from her time with Zoom, and Cisco experiences troubling vibe visions of dead birds. As Barry leads his team towards a solution to the "Metapocalypse," he encounters Zoom's most formidable lieutenant to date - Black Siren (Black Canary's Earth-2 doppelganger). Meanwhile, Joe asks for The Flash's help in curbing Wally's desire for heroics.
—statmanjeff