Before there was Glee or American Idol, there was Stagedoor Manor, a theater camp in the Catskills where big-time Hollywood casting directors came to find the next generation of stars. It's where Natalie Portman, Robert Downey, Jr., Zach Braff, Mandy Moore, Lea Michele, and many others got their start as kids. At age thirty-one, Mickey Rapkin, a senior editor at GQ and self-proclaimed theater geek, was lucky enough to go,...