Is it a conspiracy movie? A twisted abduction flick like, say, The Collector? Is it about terrorism? Alien Invasion? You won’t know from one scene to the next, and you will be kept guessing.

After a car accident, Michelle (Mary Elizabeth Winstead) wakes up in what looks like a basement. Chained to a pipe. A guy named Howard appears (John Goodman), an apparent conspiracy theorist and survivalist, spinning the implausible tale that aliens have poisoned Earth’s air and that he has saved her life by bringing her into his well-stocked underground shelter.

Sure, she says. But the third person in the shelter (John Gallagher, Jr.), Howard’s handyman, thinks it may be true. Or not.

Winstead, who I’ve always thought underrated, is spot on here, smart and strong yet vulnerable. But the movie revolves around Goodman, whose rare ability to do both loveable and deeply menacing will have you squirming.

This Twilight Zone episode on steroids works because the dread is psychological, not gimmicky. It also pokes a little fun at itself and the horror genre as a whole.

My only gripe is its misguided references to its parent movie, 2008’s fairly decent found-footage creeper Cloverfield. The connection is tenuous at best.

By the end, after you’re totally wound up and your nerves are shot, it ratchets it up one more notch in a cathartic (some are saying extraneous) finale. Big screen, please, for its most excellent use of sound. (105 min)