Vallier: The Lilies Musical is set in a Quebec prison in 1952, where Bishop Jean Bilodeau is called to hear the confession of Simon Doucet, a dying inmate who has been imprisoned for 40 years. However, Simon has a different plan for Bilodeau. He enlists his fellow inmates to perform a musical set in 1912, during their youth in Roberval, Quebec, when Bilodeau and Simon were childhood friends.

The all-male cast of prisoners take on both male and female roles, hoping to reveal the mystery surrounding Vallier's death, a young man with whom Simon was romantically involved. As the musical unfolds, we learn that Bilodeau had repressed feelings for Simon and was jealous of his relationship with Vallier. When Vallier’s mother dies, young Bilodeau seizes the moment to try and win Simon for himself. In a pivotal scene, a fire breaks out in the attic where Vallier and Simon are hiding, forcing Bilodeau to decide who lives and who dies.

By the end of the musical, it becomes clear that Simon did not call Bilodeau to confess but rather to force the bishop to confront his own past and confess his role in Vallier’s tragic fate.