Supergirl 1×18 Sneak Peek #2 “Worlds Finest” The Flash Crossover

Supergirl 1×18 “Worlds Finest” – 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, on SUPERGIRL, Monday, March 28th on CBS. Grant Gustin crosses over as The Flash. Official website: http://www.cbs.com/shows/supergirl/ Official Twitter page: https://twitter.com/supergirlcbs Official Facebook page: https://www.facebook.com/SupergirlCBS Supergirl 1×18 Sneak Peek #2/Preview “Worlds Finest” Supergirl Season 1 Episode 18 Sneak Peek #2 Supergirl 1×18 Sneak Peek #2 “Worlds Finest” (HD)