Secret's Safe with Me

A message scrawled in blood at a crime scene leads Castle and Beckett from a mysterious storage locker to the world of high society. Convinced that the storage locker holds a secret worth killing for, Castle finds evidence within that a socialite's butler was driving the car involved in a fatal hit-and-run accident. Meanwhile, Martha tells Castle that she knows about his relationship with Beckett and wants him to tell Alexis before she moves away from home to a dorm room at Columbia.