There's a new superhero in town. And National City needs The Flash. A third trailer has arrived for the exciting Supergirl crossover episode everyone has been eagerly anticipating. The plan? Catch the bad girl, with an 85% chance of punching. It's non-stop fun as these two superhero worlds collide this Monday, March 28 only on CBS.

In World's Finest, 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. Lost and confused after spiraling from his universe and landing in Kara's, The Flash asks for her help in finding his way back home. Excited to finally come face-to-face with one of the good guys, Kara agrees on one condition: The super-runner has to help her take down her ultra-competitive co-worker and screeching malefactor Siobhan, aka Silver Banshee, and Supergirl's old nemesis, Livewire.

Packed with action, excitement, and a bit of super-flirting, this is an episode you do not want to miss. Italia Ricci returns as Silver Banshee alongside Brit Morgan as Livewire. This episode will also feature recurring Supergirl stars Jenna Dewan-Tatum as Lucy Lane, Chris Vance as Non and Christopher Showerman as Tor.

RELATED: Stephen Amell Talks Arrow Season 5 Villain and Supergirl Crossover

Ever since Supergirl was picked up by CBS, fans had wondered if it was possible for this series to cross over with Greg Berlanti and Andrew Kreisberg's shows Arrow and The Flash on The CW. While they do air on different networks, both CBS and Warner Bros. Entertainment actually own The CW, with the network's name a combination of the first letters of its parent companies. The series is produced by Berlanti Productions in association with Warner Bros. Television. Greg Berlanti, Ali Adler, Andrew Kreisberg and Sarah Schechter are the executive producers of Supergirl, based on the characters appearing in DC Comics, and created by Jerry Siegel and Joe Shuster, by special arrangement with the Jerry Siegel Family.

This Supergirl and The Flash crossover could open the door for other crossover possibilities with The CW's other superhero shows, such as Arrow and the network's latest series, DC's Legends of Tomorrow. Of course, that will likely depend on how many tune in to World's Finest, airing Monday, March 28. It isn't known if this crossover will be teased or referenced in tonight's episode of The Flash, Trajectory, the show's first episode after a month-long hiatus, but we'll have to wait and see. Take a look at this new footage, and stay tuned for more from The Flash and Supergirl crossover episode, World's Finest. It's going to be something quite extraordinary!

B. Alan Orange at Movieweb
B. Alan Orange