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."

I do exactly what Diane says. I shut the door of 14 tight and stand guard all night. Marrow yowls and claws the wood until his paws bleed, but I don't open it. At dawn Mr. Avery is alive and confused, and the cat is gone. Diane finds me shaking in the hall. "You broke the rule," she whispers. "Now it's going to want someone instead. And it always gets paid."