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Watch: Supergirl & Flash Crossover Promo


DC debuted the first promo for the upcoming Supergirl and The Flash crossover, "Worlds Finest," which airs Monday, March 28th at 8pm ET on CBS.

Preview images have also been released.

Episode synopsis:

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.

The episode stars Melissa Benoist, Grant Gustin, Calista Flockhart, Chyler Leigh, Mehcad Brooks, David Harewood and Jeremy Jordan.