The Understudy

When the company's star falls to her death through a trapdoor locked an hour earlier, her overlooked understudy inherits the role, the dressing room, and the dead woman's phone — and every night on stage brings her one message closer to the person who killed her, and to being next.

You are the understudy nobody watches — until the star falls through a trapdoor that was locked an hour earlier. You get her part, her dressing room, and her phone, which keeps receiving messages meant for her.