Watch a Brand New Promo for Arrowverse “Elseworlds”

A brand new promo for the new Arrowverse crossover between Supergirl, Arrow, and The Flash, titled “Elseworlds” has been released. The crossover is set to kick off on December 9 and end on December 11.

In this new episode, Oliver and Barry wake up in a world where their lives have been switched by an evil scientist. To make matters worse, Kara also wakes up to her world changed to the point that her dear cousin isn’t exactly fighting on the side of good.

The bat signal!