They’re mid-conversation in a rehearsal studio; a lean, young Sondheim is dressed in a sweatshirt with three stripes on the sleeve, sheet music in his left hand, appearing to listen intently. Prince is clearly saying something about the show they’re rehearsing, the stub of a cigarette between two fingers, his trademark dark-rimmed glasses perched, with inexplicable balance, on his high, bald forehead. The men appear focused and also intimate—friends and collaborators since 1970, with a track record that includes, at the time of this photograph, several Sondheim classics: Company, Follies, A Little Night Music, Pacific Overtures, Side by Side by Sondheim, and Sweeney Todd. I bought this image after coming upon it in an art gallery a few years ago. My response to it was immediate, because I remembered clearly the day it was taken. I was at that very rehearsal, and so many others, as one of the twenty-eight cast members in Sondheim’s most infamous, anomalous flop: Merrily We Roll Along, a show that closed after just sixteen performances but went on to become a cult favorite.Merrily is the story of three close friends—Franklin Shepard (a composer), Charles Kringas (his lyricist), and Mary Flynn (a novelist/journalist)—and how their devoted troika splinters over time, thanks to compromises and betrayals.