Supergirl Sings Moon River In New Musical Crossover Clip

In this newest clip from Tuesday’s musical crossover episode of The Flash, a stunned Barry Allen (Grant Gustin) suddenly appears in a 1940s nightclub and hears Supergirl’s (Melissa Benoist) angelic voice singing “Moon River” — the Academy Award-winning song composed by Henry Mancini, with lyrics written by Johnn Mercer, and sung by Audrey Hepburn in Breakfast at Tiffany’s (1961).

So… what the heck is going on? “[Music Meister] puts Barry and Kara into this shared dream, this sort of nightmare,” Carlos Valdes explained to EW. “He brings them into this illusory world where their objective is to literally figure out the plot of this traditional musical comedy. It’s very self-aware. It takes place in their own heads. We embedded into the script this idea that Barry and his mom used to bond over musicals, musicals always made things better. And so, this plot is based on that idea of musicals not just as a form of escapism, but also as a form of emotional catharsis.”

He added, “Well, the thing about this dream world is it’s very much like The Wizard of Oz in the sense that Barry and Kara encounter the people that populate their daily lives, but they are different.”

DARREN CRISS (“GLEE”) GUEST STARS AS THE MUSIC MEISTER IN THE FLASH AND SUPERGIRL MUSICAL CROSSOVER – Barry (Grant Gustin) and team are surprised when Mon-El (guest star Chris Wood) and Hank Henshaw (guest star David Harewood) arrive on their Earth carrying a comatose Supergirl (guest star Melissa Benoist) who was whammied by the Music Meister (guest star Darren Criss). Unable to wake her up, they turn to Team Flash to save her.

However, the Music Meister surprises The Flash and puts him in a similar coma, one that Team Flash can’t cure. Kara and Barry wake up without their powers in an alternate reality where life is like a musical and the only way to escape is by following the script, complete with singing and dancing, to the end.

Dermott Downs directed the episode with story by Greg Berlanti & Andrew Kreisberg and teleplay by Aaron Helbing & Todd Helbing.

MORE: The Flash, Supergirl Musical Crossover Details Reveal Characters’ New Roles / The Flash, Supergirl Stars Gush Over Glee Reunion / Iris West Will Have Key Role In Musical Crossover

Based on the characters from DC, The Flash is from by Bonanza Productions Inc. in association with Berlanti Productions and Warner Bros. Television, with executive producers Greg Berlanti (Arrow, Supergirl), Andrew Kreisberg (Arrow, The Flash), Sarah Schechter (Arrow, DC’s Legends of Tomorrow) and Aaron and Todd Helbing.

“Duet” episode of The Flash will air Tuesday, March 21 at 8 p.m. ET/PT.