The episode will kick off on Supergirl, much like the four-part crossover did earlier this season, and then primarily take place in The Flash. Melissa Benoist and Jeremy Jordan will both have songs in the musical, along with non-singing appearances by J'onn J'onzz (David Harewood) and Mon-El (Chris Wood).
What may be most exciting word is that the CW revealed that Legends of Tomorrow's Victor Garber and John Barrowman — both of whom have extensive musical backgrounds — will also cameo to sing in the crossover. The Flash cast will round out the musical numbers with performances by Grant Gustin, Carlos Valdes and Jesse L. Martin.
The impetus for the musical crossover is of course the massive amount of talent that comes from both casts. Benoist and Gustin are both Glee alums while Barrowman, Valdes and Jordan both cut their teeth on Broadway (Jordan was also a series regular in Season 2 of NBC's SMASH). Martin and Garber have already had a chance to showcase their singing skills — Martin during the Earth-2 crossover on The Flash last season, and Garber earlier this season Legends during a trip to World War II era Germany.
The conspicuous absence in the singing list is The Flash's Wally West (Keiynan Lonsdale). The actor is a professionally trained dancer and his moves can be seen in the Australian teen soap Dance Academy, which is available on Netflix.
Now fans just have to wait to see who will be cast to play the musical crossover's villain — Music Meister.
The musical crossover will begin with the Supergirl episode airing on Monday, March. 20 at 8/7c on the CW and then resume with The Flash on Tuesday, also at 8/7c on the CW .
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