Supergirl: Season 1, Episode 18 - ProjectFreeTV

1 - 18: Worlds Finest

Supergirl meets the Flash. Kara gains a new ally when the lightning-fast superhero The Flash (Grant Gustin) suddenly appears from an alternate universe and helps Kara battle Siobhan, aka Silver Banshee, and Livewire in exchange for her help in finding a way to return him home.