The C.C.C. club sits on a particularly grimy stretch of Detroit's 8 Mile Road, its shabby wood-paneled facade wedged between J's Liquor Shop and a massive Mega Pawn. This boulevard, which Eminem made famous, roughly separates the city's haves from its have-nots, and the C.C.C., a notorious after-hours spot, sits squarely on the latter side. It's not the kind of place most famous rappers would spend their Monday nights. But it was here that Eminem's mentor, D12 mastermind...

"I was watching Searching for Bobby Fisher and Mark Hicks [D12's manager] put in a Jerry Garcia documentary," says Proof, who also serves as Eminem's right-hand rapper. "In this movie, he talked about never doing the same show twice. I did that to D12 sets overseas. Plus, he didn't care about record sales -- he just wanted to make fans happy."

In a nod to their...