Crossovers are never more welcome than in the comic book universe.

The CW has already included crossover episodes for their series in the past, mostly involving Arrow, Supergirl, and The Flash. However, Variety announced that Arrow will be taking a backseat in the latest (musical) collaboration.

The two episode event will take place on the March 20th episode of Supergirl and the March 21st episode of The Flash. Variety reports that the majority of the vocal action will be showcased in The Flash’s episode, appropriately named “The Duet,” although Supergirl will start the transition to the crossover at the end of their episode.

Much of the details about the crossover have been kept in secret, but we do know “Duet” will be directed by Dermott Downs. The episode will also have various names from the musical and Broadway world performing in the show, including the lead cast. Grant Gustin (who plays Barry Allen on The Flash) has previously performed songs on Glee, as has his castmate Melissa Benoist. Jesse L. Martin, Carlos Valdes, Victor Garber, Jeremy Jordan, and even John Barrowman are expected to participate in the vocal performances.

Variety also claims that the crossover has not publicly announced that they will be performing an original song during the course of the shows, but executive producer Greg Berlanti did formerly hint at the possibility.