VIDEO: Trailer for SUPERGIRL/THE FLASH Crossover Episode is Here!

Grant Gustin guest stars in the SUPERGIRL/FLASH crossover episode titled "Worlds Finest." In the episode, 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.

The episode airs Monday, March 28 (8:00-9:00 PM, ET/PT) on the CBS Television Network. Get a sneak peek below!

SUPERGIRL is an action-adventure drama based on the DC Comics character Kara Zor-El, Superman's (Kal-El) cousin who, after 12 years of keeping her powers a secret on Earth, decides to finally embrace her superhuman abilities and be the hero she was always meant to be. Twelve-year-old Kara escaped the doomed planet Krypton with her parents' help at the same time as the infant Kal-El. Protected and raised on Earth by her foster family, the Danvers, Kara grew up in the shadow of her foster sister, Alex, and learned to conceal the phenomenal powers she shares with her famous cousin in order to keep her identity a secret. Years later at 24, Kara lives in National City assisting media mogul and fierce taskmaster Cat Grant. She works alongside her friend and IT technician Winn Schott and famous photographer James Olsen, who Grant just hired away from the Daily Planet to serve as her new art director. However, Kara's days of keeping her talents a secret are over when Hank Henshaw, head of a super-secret agency where her sister also works, enlists her to help them protect the citizens of National City from sinister threats. Though Kara will need to find a way to manage her newfound empowerment with her very human relationships, her heart soars as she takes to the skies as SUPERGIRL to fight crime.