Flash-Supergirl crossover
Grant Gustin as The Flash and Melissa Benoist as Supergirl The CW/CBS

Fans would enjoy The Flash and Supergirl musical crossover as it is going to be packed with song and dance. The CW has released the synopsis for the special episode, which will kick off at the end of Supergirl season 2 episode 16.

The Music Meister will attack Supergirl in the episode, and Mon-El alongside Hank Henshaw will crossover to The Flash universe to seek help for Kara Danvers. Supergirl season 2 episode 16 is titled Star-Crossed, which will air on 20 March at 8pm EST.

The official synopsis reads as follows:

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 network has confirmed that Glee actors Grant Gustin (who plays Barry) and Melissa Benoist (who plays Kara) will be singing in the episode alongside, Broadway veterans Jesse L Martin (Joe), Victor Garber (Dr Stein), John Barrowman (Malcolm Merlyn), Jeremy Jordan (Winn) and Carlos Valdes (Cisco).

Co-showrunner Aaron Helbing revealed that Iris West will have a key role in the upcoming musical extravaganza.

He told TV Line, "She [West] plays a pretty key role in the musical episode. The story really centers around Iris. Aside from Barry (Grant Gustin) and Kara (Melissa Benoist), Iris plays a huge role in the musical."

The 2nd part of the mashup continues on The Flash season 3 episode 17 titled Duet, which will air on 21 March at 8pm EST.

Here is the full synopsis for the episode:

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.