The very first official image from the new Supergirl and The Flash crossover episode "Supergirl, Worlds Finest" has been released! It's a very clever mirror image of the classic comic book cover. In the original comic book image, Superman or the Man of Steel if you like is running up against the fastest man alive. But in this context the image shows Melissa Benoist's "Girl of Steel" running up against Grant Gustin's The Flash.
Warner Brothers has described the plot as follows - SPOILERS!
"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."
This episode is written by Executive Producer Greg Berlanti. It has a telepplay by Andrew Kreisberg and Michael Grassi. The episode is Directed by Nick Gomez.
The episode airs in America on March 28th.