Take Shelter is a horror film. Or an end-of-the-world film. Or a family drama. Or a study of the ravages of mental illness on a man and his family. Or all four. Or not. If it weren’t for that ending, I might be able to tell you.

I really wanted to like this film, and it holds up on several fronts. It’s a demonstration of some of the best of modern acting (Michael Shannon, Jessica Chastain) coupled with a direction and script that highlight the pauses and awkward moments of real life. But that ending.

Michael Shannon (Oscar nomination for best supporting acting for Revolutionary Road) is the walking definition of “disturbed.” If Last Man Standing is the possible name for every one of Bruce Willis’s movies, then perhaps Mr. Shannon could take the name Disturbia for every one of his films. He’s not creepy, just disturbing. Here, his body language is an acting class of discomfited containment. It’s a marvelous performance, and not a bit actorly. And I could tell you how well it fit into the entire film if it weren’t for that ending.

Jessica Chastain (Tree of Life, The Help, The Debt) is the discovery of this year, and she nails her character perfectly here. It’s a lovely, fully-realized performance that never overreaches. Her character is at times natural and at ease, at other times torn or focused or determined or simply aching with worry. She plays a “normal” woman who loves her husband and child, and is giving without being a doormat. She’s not larger than life, nor smaller. She’s real and her character breathes.

While others can argue about whether or not the nightmares/hallucinations are real or imagined or prophetic—and they will—I want to hit on another, perhaps stronger element of the film. It can be enjoyed on one level as an actors’ showcase, but it’s even stronger as a film that consistently plays with cliché and viewer expectations.

The film begins with a sound-and-image combination that introduces the idea and feeling of foreboding. Of course that works well with the main plot of the “are they real or not?” visions that follow.  But that feeling of dread builds throughout because of how the film denies our expectations. We expect that this is the scene where he is going to hurt his family; he doesn’t. We know he’s going to do such-and-such now; he doesn’t. Yet the specter of violence hangs over the film like the clouds that inhabit the frame. We never quite know what is going to happen, or when the “expected” is going to occur. Even when Shannon gets his big anger scene that every performance like this “invariably” leads to, it’s not the big actor demonstration we expect, and it’s all the stronger for it. His character is not an especially articulate man, especially when under pressure. It’s a logically powerful but uncomfortable moment, because instead of seeing the furniture being deservedly chewed by an excellent actor who finally gets his moment, we see a frustrated, confused, yet passionate man who can’t quite express himself as elegantly as Aaron Sorkin might like him to. Like the actions that we expect or fear but don’t end up seeing, this is another moment that hits the refresh button on the film.

For those eager to see it, please know that this is a s-l-o-w-m-o-v-i-n-g film. That is one of its great strengths and the source of much of its power. It’s in these moments that are normally left on the cutting room floor in most American films, even independent ones, that the film fills with dread and fear, and that move us closer to the edge of our seats.

And for those eager to see it who like endings that really explain things—sorry. This one won’t give you that. The questions that ending raises are the stuff of many a discussion, and is a valid choice. It’s also the reason the film hasn’t made back its budget. Americans like answers, or at least stronger and more defined possibilities. The ending was visually beautiful, intriguing, confusing, and more of a wet blanket than a satisfying release or a thought-provoking twist.