The CW has expanded its DC Comics universe over the past few years; though initially kicked off in Arrow, the network used its flagship series to introduce Barry Allen (Grant Gustin) before spinning the character off into his own series on The Flash. Since then, The CW launched the time-travel ensemble series Legends of Tomorrow starring characters from both Arrow and The Flash - in addition to certain new heroes and villains. Then, The CW welcomed Kara Danvers (Melissa Benoist) to their DC TV universe with the second season premiere of Supergirl on the network.

Late last year, Supergirl joined the heroes of Arrow, The Flash, and Legends of Tomorrow for the Invasion! crossover event, but another - albeit smaller - crossover is still in the works. Arrowverse producers confirmed last summer that The Flash and Supergirl will team up for a musical crossover event as they battle the recently confirmed villain Music Meister. Now, more details emerge concerning the crossover.

EW is reporting the musical team-up is set to kick off in the March 20th episode of Supergirl then continue in the March 21st episode of The Flash, titled 'Duet'. The report additionally confirms who will have singing roles: Barry, Kara, Supergirl's Winn Schott (Jeremy Jordan), The Flash's Joe West (Jesse L. Martin) and Cisco Ramon (Carlos Valdes), as well as Legends of Tomorrow's Professor Martin Stein (Victor Garber) and Malcolm Merlyn (John Barrowman). Fellow Supergirl characters J'onn J'onzz (David Harewood) and Mon-El (Chris Wood) will appear in the crossover with non-singing roles.

The Flash Supergirl Music Meister

The report additionally reveals that the musical crossover will only kick off at the end of Supergirl's March 20th episode, similar to the show's lead in to the Invasion! story arc. Meanwhile, Dermott Downs has been confirmed as the director of 'Duet' - disproving earlier rumors The CW had tapped director Joss Whedon (The Avengers, Buffy the Vampire Slayer). Downs is a veteran of both The Flash and Supergirl, and in fact directed The Flash's 'Invasion!' episode. The CW has yet to announce who will portray Music Meister in the crossover episode.

In terms of how the crossover will be set up, fans may be disappointed that it won't run throughout two full episodes, as was initially reported. Rather it seems the musical event will largely take place on The Flash - though that may make the most sense story-wise since Music Meister isn't necessarily known for jumping between worlds. Introduced on Batman: The Brave and the Bold, his power allows him to hypnotize others and force them to sing.

Still, given the characters expected to have signing parts, it seems The CW has included all of the Arrowverse actors (who currently have major roles on the shows) with a background in musical theater. Both Gustin and Benoist appeared on Fox's musical dramedy Glee, while Jordan, Martin, Garber, Barrowman, and Valdes have performed on Broadway. So, it seems the creative teams of The Flash and Supergirl are putting together a memorable musical event - which fans will get the chance to see near the end of March.

Next: Kevin Smith Wants to Direct An Arrowverse Crossover Episode

Supergirl season 2 returns with ‘Supergirl Lives’ Monday January 23 at 8pm on The CW. The Flash returns with ‘Borrowing Problems from the Future’ on Tuesday, January 24th at 8pm on The CW.

Source: EW