Supergirl 1x18 "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. Subscribe to tvpromosdb on Youtube for more Supergirl season 1 promos in HD!

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Supergirl 1x18 Promo/Preview "Worlds Finest" Supergirl Season 1 Episode 18 Promo Supergirl 1x18 Promo "Worlds Finest" (HD)