Even if you're not a CW superhero-show maniac, you must be wondering how the hell The Flash and Supergirl are going to pull off a musical episode. (Plot-wise, anyway; Grant Gustin and Melissa Benoist were both on Glee, so.)

Now a teaser for the March 21 episode shows fellow Glee alum Darren Criss as the villainous Music Meister. He announces that the Flash and Supergirl will find themselves transported to a movie-musical world—without their powers. "Reach the end of the plot, you get to go home," he says. "Although I should mention, if you die in here, you die out there."

The CW's official description for the crossover elaborates a bit:

"Barry and team are surprised when Mon-El (guest star Chris Wood) and Hank Henshaw arrive on their Earth carrying a comatose Supergirl who was whammied by the Music Meister. 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."

Den of Geek notes that the Music Meister is based on the comic book character of the Music Master, who "uses his singing skills to hypnotize heroes, villains and ordinary people to do his bidding."

Also confirmed to sing are Carlos Valdes, Jeremy Jordan, Jesse L. Martin, John Barrowman and Victor Garber.

Next, watch artists tell Fuse who they think is tougher, Batman or Superman: