EXCLUSIVE:   Gary Dauberman ‘s Coin Operated has secured the rights to  Rest Stop , a recently published horror novella by Nat Cassidy , with an eye toward developing a feature adaptation. Cassidy will adapt the screenplay, with Dauberman and Mia Maniscalco to produce through Coin Operated. Rest Stop  follows a young musician who finds himself locked inside a gas station bathroom in the middle of the night by an unseen assailant, caught between the horrors on the other side of the door and the horrors rapidly skittering down the walls inside. The story is part of Cassidy’s collection,  I Know A Place: Rest Stop and Other Dark Detours , which Shortwave Publishing and Simon & Schuster released on May 5. “I like to describe this novella as ‘ Green Room  meets  Gerald’s Game ,'” Cassidy told us.…