The night shift is quiet except for the machines breathing down the hall. The gray cat, Marrow, walks ahead of me like he owns the place. By March I figured out the rule nobody says out loud: wherever Marrow curls up to sleep, that bed is empty by dawn. Tonight he stops outside Room 14. Then he turns and looks straight at me with flat yellow eyes.

I check my chart. Room 14 is Mr. Avery, and he's stable tonight. No reason for the cat to pick him. I crouch down and try to shoo Marrow away from the door. He doesn't move. He just keeps staring at me, waiting to see what I'll do.

I call Diane, the senior nurse who trained me. She picks up on the first ring even though it's 3 a.m. "Which room?" she asks. When I say 14, there's a long silence. "Don't let the cat in," she says. "Whatever you do tonight, keep that door shut."