Blue Moon chronicles a quietly tragic evening near the end of the life of Hart, played by Linklater’s frequent collaborator Ethan Hawke. Written by Robert Kaplow, it conjures a scenario in which Hart, known for songs like "My Funny Valentine," attends the opening-night party for Oklahoma! in March 1943. That venerated show would mark the first collaboration between Richard Rodgers, formerly Hart's longtime musical partner, and Oscar Hammerstein II. Dramatic irony means we know that Hart will die just a few months later, and Rodgers and Hammerstein will revolutionize the Broadway musical.