Next week, two of The CW's most beloved superheroes will join forces yet again, when The Flash and Supergirl team up for their highly-anticipated musical crossover, which begins with the Monday, March 20 episode of Supergirl, and the majority of the story being told during The Flash episode on Tuesday, March 21. Today we have the trailer and tons of photos from Duet, which give us our first look at the villainous Music Meister, played by Darren Criss.

This trailer, which debuted on The CW YouTube channel, introduces Music Meister, with this episode serving as a reunion for Darren Criss and both Grant Gustin and Melissa Benoist. Darren Criss is best known for playing Blaine Anderson on Fox's hit musical series Glee, which Melissa Benoist and Grant Gustin both recurred during Glee's successful run, before taking on their current superhero roles. They will both have to put their musical talents to the test in this episode, where their characters are trapped by the nefarious Music Meister.

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 directs the episode with story by Greg Berlanti & Andrew Kreisberg and teleplay by Aaron Helbing & Todd Helbing. It was also recently announced that Award-winning songwriters Benj Pasek and Justin Paul have penned an original song entitled "Runnin' Home to You" for The Flash/Supergirl musical episode. Grant Gustin will perform the song in The Flash episode entitled "Duet," airing Tuesday, March 21, 8:00-9:00 pm ET/PT on The CW. In addition to "Runnin' Home to You," The Flash episode will feature another original song penned by Crazy Ex-Girlfriend star and executive producer Rachel Bloom and Tom Root, entitled "Super Friend."

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This musical episode will feature singing performances from Grant Gustin, Melissa Benoist, Jesse L. Martin, Victor Garber, Carlos Valdes, Jeremy Jordan and John Barrowman, while also including non-singing guest star appearances from Supergirl's David Harewood and Chris Wood. This crossover format will be similar to the "DC Week" crossover format, where the Monday episode of Supergirl is by and large a "normal" episode, which introduces crossover elements at the very end, setting up the full crossover in The Flash. Take a look at the new trailer for The Flash and Supergirl crossover, along with the photos below.

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