If horror movies have taught us anything it’s this: Don’t go anywhere. Don’t leave your house, and if you do leave your house, don’t leave your hometown. And if you do leave your hometown, don’t go out to the middle of nowhere. And if you do go out to the middle of nowhere and someone asks you all to surrender your cell phones, skip to the end and run away in terror right now. It’ll save everybody — you and the killer cultists included — a lot of bother.

Writer/director Mark Anthony Green’s “Opus” is the latest in a long line of films where city folk are invited to somewhere creepy, ignore obvious red flags for most of the runtime, then have the audacity to act surprised when scary things happen. Specifically this is the creepy cult version, where everyone they meet is a...