Trailers for individual TV series episodes are a thing that probably shouldn't be, but that's where we are in today's "hype everything" culture. On occasion it can be kind of cool, like with the release of the trailer for "World's Finest", the crossover episode of Supergirl featuring Grant Gustin of The Flash. Here's the synopsis for the episode, the 18th of the season...
“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, aka Silver Banshee, and Livewire in exchange for her help in finding a way to return him home.”
CBS will air "World's Finest" on Monday, March 28th at 8pm EST.