Worlds Finest

"Worlds Finest" is the upcoming eighteenth episode of the first season of Supergirl. It will air on March 28, 2016. It will act as a crossover between Supergirl and The Flash.

Synopsis
Kara gains a new ally when the lightning-fast superhero The Flash 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.

Behind the scenes

 * The episode's title is a reference to the World's Finest comics, which would have Superman and Batman crossover.
 * The promotional poster released for the episode is a reference to the cover of Superman #199, in which The Flash crossed over to verse Superman.