'Supergirl,' 'Flash' to cross over in musical episode

The CW recently announced that "Supergirl" and "The Flash" will have another set of crossover episodes in the form of musicals.

The crossover will begin on "Supergirl." Teri Hatcher, who plays a villain, will visit National City, and she will put Supergirl (Melissa Benoist) on "high alert." The episode will culminate with the Music Meister, played by Darren Criss, attacking and knocking out the titular character.

The story will then follow Barry (Grant Gustin) as he was surprised by Mon-El (Chris Wood) and Hank Henshaw (David Harewood), who have brought a comatose Supergirl with him in his version of Earth. He also gets knocked out by the Music Meister. The two unconscious superheroes will then wake up to an alternate reality where they are forced to sing and dance their way to escape from their comatose state.

Aside from the two leads, the other cast members of both shows, such as Jesse L. Martin, Victor Garber, John Barrowman, Jeremy Jordan, and Carlos Valdez, are also expected to sing and dance in the crossover episodes.

Benj Pasek and Justin Paul, who wrote "City of Stars" in "La La Land," also wrote a number, titled "Runnin' Home to You," for the crossover episode. This will be performed by Gustin. Another song that will be performed is "Super Friend," which was written by Rachel Bloom, the creator and star of "Crazy Ex-Girlfriend." This is a duet that will be performed by Gustin and Benoist.

Fans of both shows may recall that both Benoist and Gustin were part of "Glee," a series where musical performances are integral to its story. Criss was also a regular on the said show. Interestingly, the original actor who played the Music Meister was Neil Patrick Harris, who voiced the villain in the animated series, "Batman: The Brave and the Bold," and who also had a guest appearance on "Glee."

Episode 16 of "Supergirl" will air on March 20, Monday, at 8 p.m. ET, while episode 17 of "The Flash," titled "Duet," will air the following day, March 21, Tuesday, also at 8 p.m. Both shows air on The CW.