Gleealums Grant Gustin and Rapsa (2025)Melissa Benoist will reunite with their former co-star Darren Criss in The Flash's upcoming musical crossover with Supergirl, and Mashablehas an exclusive first look at the trio in action.

Gustin doesn't seem particularly thrilled to see his fellow Warbler in the sneak peek image above -- but that's probably because Criss is playing the villainous Music Meister -- a metahuman whose powers cause people to spontaneously erupt into song and dance when they hear his voice.

The CW has also released additional photos and the first teaser trailer from the episode, titled "Duet," which will premiere on March 21.

The action begins when Music Meister (Criss) attacks Supergirl and puts her in a coma in the March 20 installment of her eponymous show, prompting Mon-El (Chris Wood) and Hank Henshaw (David Harewood) to arrive on Earth-1 for help from Team Flash. 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.

The musical installment will feature a combination of original songs and covers, including one penned by La La Landlyricists Benj Pasek and Justin Paul -- who wrote the Oscar-winning song "City of Stars" -- titled "Runnin' Home to You."

The episode will also feature a track written by Crazy Ex-Girlfriendstar Rachel Bloom and Tom Root, titled “Superfriends.”

The Flashand Supergirl's musical crossover, "Duets," airs Tuesday, March 21 at 8 p.m. on The CW.