Get a Behind-the-Scenes Look at the ‘Supergirl’/’Flash’ Crossover Episode!

“Extra” has a special behind-the-scenes look at Monday’s “Supergirl”/”Flash” crossover event.

Watch as stars Melissa Benoist and Grant Gustin give fans an inside look!

In the episode “World’s Finest,” Barry (The Flash) arrives in National City from an alternate universe and helps Kara (Supergirl) battle Siobhan, aka Silver Banshee, and Livewire in exchange for her help getting home.

Tune in March 28 at 8 p.m. on CBS to see the two superheroes in action.