<Tr> <Td> ← Previous "Into the Speed Force" </Td> <Td> Next → "Abra Kadabra" </Td> </Tr> <Tr> <Td_colspan="2"> List of The Flash episodes </Td> </Tr> <P> "Duet" is the seventeenth episode of the third season of The CW television series The Flash, which aired on March 21, 2017 . The episode was written by Aaron Helbing and Todd Helbing from a story by Greg Berlanti and Andrew Kreisberg, and was directed by Dermott Daniel Downs . The episode features a musical crossover with Supergirl and reunites Grant Gustin and Melissa Benoist with their former Glee co-star Darren Criss, who portrays the Music Meister . Jesse L. Martin also reunites with Jeremy Jordan, with whom he previously worked in the 2012 musical film Joyful Noise . The story begins at the end of the Supergirl episode "Star - Crossed", which aired on March 20, 2017, which saw Kara Danvers / Supergirl (Benoist) being put into a coma by Music Meister, with Mon - El (Chris Wood) and J'onn J'onzz / Martian Manhunter (David Harewood) bringing her to Earth - 1 in hope that Team Flash can save her . </P> <P> J'onn J'onzz and Mon - El of Earth - 38 arrive on Earth - 1 with a comatose Kara Danvers / Supergirl, in hope that Team Flash can revive her . They warn Barry Allen / Flash that the escaped prisoner, Music Meister, claimed he would be coming for him too . Meister appears inside S.T.A.R. Labs and Barry and Wally West / Kid Flash confront him, but Meister attacks and places Barry in a similar coma . Barry wakes up to find himself without his powers in a musical world where he discovers Kara singing in a nightclub ("Moon River") and where everyone resembles people they know in the real world . Meister tells Kara and Barry that if they follow the script, they will return to the real world . He warns them, however, that if they die in this world, they die in real life ("Put a Little Love in Your Heart"). Barry and Kara are forced to work as singers in a nightclub run by Cutter Moran (Malcolm Merlyn), with Grady (Winn Schott) working as a piano player, Pablo (Cisco Ramon) as a waiter, and Digsy Foss (Joe West) and his husband (Martin Stein) as two gangsters opposing Cutter . Digsy and his husband kidnap Barry and Kara and tell them to find their daughter, Millie Foss (Iris West), whom they believe is being held hostage by Cutter . </P>

What episode is the flash and supergirl crossover musical