This article contains spoilers for The Flash episode – Duet.
The musical episode of The Flash has finally arrived and, unlike other episodes, you have to judge this one on a different set of merits. Having it be a crossover between Flash and Supergirl means there was a certain amount of setup needed, with a minute or two having taken place on Supergirl the previous night. But the gist of the plot is that Music Meister (Darren Criss) traps Barry Allen (Grant Gustin) and Kara Danvers (Melissa Benoist) into a shared alternate reality that is basically a musical. And to get out, they must play along with the script and survive until the end. Which of course means that it's not so simple.
Music Meister has some very different powers here than we saw from him in his Batman: Brave and the Bold appearances. He can put people into alternate realities and steal their powers for himself. Though looking at all that he did in the episode and how he did it, he appeared to be similar to a 4th Dimension imp like Mr. Mxyzptlk. That would explain a lot of the things he knew, like how both Barry and Kara were having relationship issues and how Wally West (Keiynan Lonsdale) was dealing with confidence issues. Music Meister, in the end, seemed like he wanted to help the heroes… which again goes against the version we've seen before, but this is a different universe after all.
Mon-El (Chris Wood) and J'onn J'onzz (David Harewood) bring Kara to Earth-1 because that's where Music Meister went. He then appeared and put the same whammy on Barry and pushed at Wally a bit before taking off with super-speed. So while Barry and Kara dealt with the musical world, Wally, J'onn and Cisco Ramon (Carlos Valdes) tried fighting him in the real world. Which they do with some pretty good teamwork. But we learn that Music Meister wanted to be captured… again, he is much more omnipotent in this version.
In the musical world, Barry and Kara are signers working for Cutter (John Barrowman) who demands a new number from them. At the club there's a pianist (Jeremy Jordan) and a bus boy (Valdes). They get taken by two gangsters (Jesse L. Martin, Victor Garber) who want help finding their daughter (Candice Patton), who turns out to be in love with Cutter's son (Wood). It's a bit of a West Side Story / Fantastiks thing going on with the gangsters going to war. But the whole thing is to help Barry and Kara realize their feelings about Iris and Mon-El and it takes the latter two's entrance into the reality to save the day.
The story was fun, a bit silly and kind of rushed at the end, but they worked in quiet a few musical numbers. Benoist sings Moon River, which was a good rendition but kind of mellow to start off with. The group version of Put A Little Love In Your Heart with Criss, Barrowman, Jordan and Valdes was one of the best numbers as well as Barrowman, Garber and Martin doing More I Cannot Wish You. There is a cute number called Super Friends performed by Gustin and Benoist and written by Rachel Bloom of Crazy Ex-Girlfriend and Tom Root. This was the first chance in the episode for Gustin to sing and where it was a fun number, it wasn't very vocally challenging. Surprisingly Gustin's solo song came at the end of the episode, back in the real world where he used an original song called Running Home To You by Benj Pasek and Justin Paul to propose once again to Iris. This song really showcased Gustin's vocals well.
The episode was fun and meant to be. Both Barry and Kara comment on how much easier things are in musicals and there are times that Barry just sits down and watches as people sing. The story moved both series along a little, getting past the romantic roadblocks both heroes were having. Plus, it got to remind fans just what wonderful voices the cast has. Though I'm surprised that neither Wood nor Patton got a chance to sing.
David Dastmalchian gets to join yet another comic book universe, having already been in Ant-Man and Gotham. Now the actor appears as the time-traveling techno-magician Abra Kadabra who claims to know who Savitar is. There has been a popular fan theory that Kadabra is in fact Savitar, using his technology to simulate super-speed, but he might also know who the future Flash is… if that is what Savitar is claiming to be. It's all a bit confusing at this point.