The Other Josh Coehn is based on true stories, but whose and how many people’s is another question—one that co-composers/lyricists/book-writers Steve Rosen and David Rossmer refuse to answer.

“We like for everything to be a surprise,” maintains Rosen. So what is the show about? It’s Valentine’s Day, and Josh Cohen’s apartment has just been robbed. (Yes, someone’s apartment really did get robbed.) The only belonging he has left is a Neil Diamond CD. (This may be a plot device….) For what happens next, you’ll have to venture to Paper Mill Playhouse in Millburn N.J., where the show is running through March 16.

Rosen and Rossmer met at French Woods Performing Arts Camp and sealed their fate as comedy collaborators when they made each other laugh during an improv scene. They worked together on the cabaret series “Don’t Quit Your Night Job,” among other things, and when Rosen moved out to L.A. “for a change,” Rossmer flew out to write and pitch TV ideas with him. “This is how you know that we’re theatre people,” Rosen jokes. “We went out to L.A. to write TV shows, and we wound up writing a musical.”

However, the show had no readings or workshops before its first production, under the title V-Day, at the 2010 New York Musical Theatre Festival. In addition to writing, Rosen and Rossmer both star and play in the band, as do all the actors. “We would rehearse all day and write all night,” Rosen explains of their 21-hour workdays. “And then the next morning we would call our friends who worked in offices and they’d help us make copies.”

Lily Fan, a lawyer and fledgling producer, attended the final performance at NYMF and optioned the show, which led to a second production at New York’s Soho Playhouse, under the current title. After the show received accolades, Hurricane Sandy robbed lower Manhattan of electricity and Josh Cohen of 10 performances. “When the power came back, there were lines of people coming to see it,” Rosen remembers. One of them was Broadway producer Kevin McCollum (Avenue Q, Motown), who is producing the show at Paper Mill.

Moving from 199 seats at Soho Rep to 1,200 seats at Paper Mill is quite a change. “You can’t fight the space you’re in,” ventures director Ted Sperling. “You have to embrace it.” The show is “supposed to feel like a concert,” according to Rosen—which is a good reason to bring on a new set designer David Korins, and to hire an additional cast member to help fill out the stage and the sound.

“Our dream is to bring this show to Broadway, and then to bring it to every theatre in the country,” Rosen says. “It would be nice if this becomes the Valentine’s version of A Christmas Carol.”