Tread Perilously finally meets the Fastest Man Alive with the musical episode of The Flash, "Duet."

When the Music Meister mesmerizes Kara and Barry, they awake in a movie musical about crime, forbidden love and their own romantic misunderstandings. Back on Earth-1, Wally must work with Cisco and J'onn to bring an end to the Music Meister's crime spree. As the musical unfolds, Kara and Barry learn a song and attempt to negotiate a truce between warring gang factions. The fact the gang leaders have incredible voices is neither here nor there. But will Iris and Mon-El find a way to awaken their estranged paramours before time runs out?

After digressing into conversation about The Flash in other episodes, Erik and Justin's chance to talk about the show properly leads to digressions about Chuck Lorre, Man of Steel and The Transformers. They also discuss the Iris Problem and better ways to write Savitar. Justin remembers Captain Cold while Erik suggests Grodd as a season villain. Erik reveals why he loves Mon-El and discusses how it put him at odds with the Rotten Tomatoes readership. The overall problem with the romantic leads on The CW superhero shows gets highlighted and the pair examine the way musical episodes tend to be used in action shows.