I rubbed my eyes and checked the clock on my laptop. Eleven p.m. The humanities building was dead silent except for the hum of the air conditioning. 

I had been here since dinner, grinding through my final thesis on modern architecture. The big lecture hall was empty now, rows of desks stretching out like shadows under the low emergency lights. 

Everyone else had gone home hours ago. Professors, students, even the janitors. Or so I thought.

I heard it first. A soft squeak of wheels rolling down the hallway. 

Then the door at the back of the hall creaked open. I looked up from my screen and saw him. A...