The Flash 3x17 "Duet" Musical Crossover Promo
The musical crossover kicks off Monday, March 20th with Supergirl, "Star Crossed":
A new villain (guest star Teri Hatcher) comes to National City, putting Supergirl (Melissa Benoist) on high alert. Meanwhile, Winn’s (Jeremy Jordan) girlfriend, Lyra (guest star Tamzin Merchant), gets Winn in trouble with the law. Maggie (guest star Floriana Lima) attempts to help Winn but old loyalties get in the way. The Music Meister (Darren Criss) attacks Supergirl.
The second part airs on Tuesday, March 21st on The Flash, "Duet":
“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.