Flash-Supergirl crossover: Behind the scenes video

Get ready for the super team-up that brings the Flash into the world of Supergirl.

In the upcoming Flash-Supergirl crossover, Kara (Melissa Benoist) gains a new ally when the lightning-fast superhero the Flash (Grant Gustin) suddenly appears from an alternate universe and helps Kara battle Siobhan, a.k.a. Silver Banshee (Italia Ricci), and Livewire (Brit Morgan) in exchange for her help in finding a way to return him home.

Check out a behind-the-scenes look at the crossover above, and get all the scoop on what’s in store here.

The Flash-Supergirl crossover will air Monday at 8 p.m. ET on CBS.

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  By Natalie Abrams