‘The Flash’/’Supergirl’ Musical Crossover: 10 Spoilers We Just Learned

The Flash and Supergirl are about to cross paths once again — only this time, with some added singing and dancing. The two heroes will team up for an epic musical crossover, set to air on The CW in March. Though specific details about the event have not been released, fans have recently gotten a few hints as to what to expect from the upcoming episodes. Here are 10 spoilers we just learned about the anticipated crossover:

1. It will take place over two nights

Supergirl / Flash crossover

Supergirl meets the Flash | CBS

As was the case for the network’s recent “Heroes vs. Aliens” crossover, the two-part musical event will kick off at the very tail end of Supergirl. But most of the action will be saved for the following night during The Flash portion of the event, which is appropriately  titled “Duet.”

[Update 3/3/17]: The CW has just released the official summaries for both episodes of the upcoming crossover, seen below:

Supergirl: “Star-Crossed”
A new villain (guest star Teri Hatcher) comes to National City, putting Supergirl on high alert.  Meanwhile, Winn’s girlfriend, Lyra, gets Winn in trouble with the law. Maggie attempts to help Winn but old loyalties get in the way.  The Music Meister attacks Supergirl.

The Flash: “Duet”
Barry and team are surprised when Mon-El and Hank Henshaw arrive on their Earth carrying a comatose Supergirl who was whammied by the Music Meister. 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.

2. These characters will be involved

Cisco on The Flash

Cisco on The Flash | The CW

Grant Gustin’s Barry/The Flash and Melissa Benoist’s Kara/Supergirl will obviously be the main stars of the crossover, but who else will be showing off their musical chops during the two episodes? The CW has confirmed these names to appear: Broadway vets Jesse L. Martin (who plays The Flash‘s Joe), Victor Garber (The Flash‘s Dr. Stein), John Barrowman (Legend of Tomorrow‘s Malcolm Merlyn), and Jeremy Jordan (Supergirl‘s Winn), as will Carlos Valdes (The Flash‘s Cisco).

David Harewood (Supergirl‘s Hank) and Chris Wood (Supergirl‘s Mon-El) will also appear in “Duets,” but they’re not expected to be joining in on the musical parts.

3. Music Meister will be the primary villain

Music Meister

Music Meister | DC Comics

As executive producer Greg Berlanti confirmed several months ago, the main antagonist of the crossover will be Music Meister. The famous Batman villain was bullied as a child in choir, but soon discovered that he could hypnotize people by singing in a high octave. He now has the power to control people through song, which explains why the heroes will suddenly feel the urge to break into song.

4. It will be a Glee reunion

Darren Criss

Darren Criss | Noam Galai/Getty Images

Benoist and Gustin are both famously Glee veterans, but they won’t be the only alumni from the musical show to show off their skills in the upcoming crossover. Fellow Glee grad Darren Criss has been tapped to play the big bad of the episodes, Music Meister.

“With our Flash and our Supergirl being Glee alums, how could we not have them go up against another Glee favorite like Darren Criss?” Executive Producer Andrew Kreisberg told TVLine of the casting. “We have been blown away by his talent over the years and we can’t wait to see what he brings to the Music Meister.”

5. It will feature some original songs

The Flash - Season 3

The Flash | The CW

The crossover is expected to include mostly covers of songs, but Berlanti and Kreisberg have confirmed that it will also feature at least some original tunes. It’s unclear just how many of each type of song we will see, but from the sounds of it, fans can expect one wild musical ride.

“The musical will just be awesome. It’s gonna be fun,” Kreisberg said of the upcoming episodes. “It’s funny, we have villains that can split the earth in half. We have villains that can run at the speed of light. What’s so crazy about a villain that can make you think your friends are singing and dancing in front of you?”

6. Some well-known song writers will be involved

Rachel Bloom

Rachel Bloom | Christopher Polk/Getty Images

Crazy Ex-Girlfriend co-creator and star Rachel Bloom, will be writing an original song for the crossover episode. The song is titled “Superfriends” and will be a duet between Benoist’s Kara and Gustin’s Barry. As a fellow CW star herself, Bloom reportedly reached out and offered her songwriting services to the show after hearing of the crossover. “I am so excited to contribute more to the upward trend that is musicals in television and film,” she said, per BuzzFeed. “Music can be one of the most amazing and efficient forms of storytelling and character development. Also, it was really fun to write a comedy song for two superheroes.”

She’s not the only notable name to contribute an original song to the crossover. Benj Pasek and Justin Paul, the songwriting team behind La La Land’s “City of Stars” and the Broadway musical, Dear Evan Hansen, will also be penning a track for the crossover. It will be called “Runnin’ Home to You” and will be performed by Gustin’s Barry — presumably to his love interest, Candice Patton’s Iris.

7. The director

Dermott Downs

Dermott Downs | Paul Hawthorne/Getty Images

Dermott Downs has been tapped to direct The Flash half of the crossover. Since that episode will maintain the bulk of the action, that effectively means that Downs will be overseeing the majority of the musical event. Luckily, he has plenty of experience working on both shows — his previous DC TV credits include Supergirl’s “For the Girl Who Has Everything” episode and The Flash’s installment of the “Heroes vs. Aliens” crossover.

8. What we’ve seen so far

The CW has yet to release any official photos or a trailer for the upcoming crossover. However, fans have been able to catch an early glimpse of Criss as Music Meister via a few leaked on-set photos. The pictures capture Criss’ Music Meister by himself, as well as on set with Carlos Valdes’ Vibe and Keiynan Lonsdale’s Kid Flash.

9. The episode will have a lasting impact

Supergirl Season 2

Supergirl Season 2 | The CW

While this crossover will be different than anything either The Flash or Supergirl have done before, that doesn’t mean it will be a throwaway episode. The two-part event will have an impact on both heroes moving forward.

“When we get to the musical episode, both Barry and Kara will find themselves at pivotal crossroads on their respective series,” Kreisberg described, per Entertainment Weekly. “The experience of going through the musical will have a great impact on both series moving forward.”

10. The release date

Supergirl and The Flash

Supergirl and the Flash | CBS

The highly anticipated two-part musical crossover will kick off on Supergirl on Monday, March 20. It will then pick up during The Flash‘s time slot on Tuesday, March 21. Both superhero shows air at 8 p.m. EST on The CW.

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