Nyctophobia

You have a job. That job is to be a security guard during the night shift at a local office complex. You and Marley do it every night. Get decent pay for it too. Enough to keep you going.

Anyway. Tonight, Marley's just called in sick, so you gotta do the shift alone. Shouldn't be bad, right? Well, the power's just gone off, and I don't think you're alone anymore...