You can picture Adam Green, the writer and director of “Frozen,” sitting on a ski lift one day, idly thinking, “What if I fell off? How high above the ground am I? No! What if the lift stopped moving and they couldn’t get it started? What if I was trapped here!” We all have our moments of morbid fantasizing, but what separates Adam Green from me and you is that he turns his dark “what if?” scenarios into movies. His “Hatchet” had tourists terrorized in the swamps of Louisiana; “Frozen” pits the heroes against Mother Nature herself, that wanton trollop.

The setting is a ski resort in New England, where three college students are trying to talk their way onto the lift without buying tickets. Dan (Kevin Zegers) and Joe (Shawn Ashmore), best friends since grade school, come skiing here regularly, but today Joe is miffed because Dan has brought along his girlfriend, Parker (Emma Bell), in a flagrant violation of the Bros Before Hoes policy.

No one likes being the third wheel; it doesn’t help that Joe and Parker don’t really get along, each jealous of the other’s relationship with Dan. It’s the same old story: “We haven’t seen you at Fezziwig’s for dollar pitcher night all semester!” Joe complains. What, Dan would rather spend time with his beautiful girlfriend than drink cheap beer? It’s like Joe doesn’t even know him anymore.

But who cares about any of this? Not you, that’s for sure, and especially not with the self-consciously hip banter that passes between the three. (I like Green’s ideas, but the dialogue is the movie’s weakness, and all three of these characters are jerks.) Soon enough, the film gets to the point, with the ski lift shutting down while Joe, Parker, and Dan are still on it. What’s more, it’s Sunday night, and the resort doesn’t open again until Friday. They’re too high above the slope to jump off. They’re trapped.

This is a simple variation on the familiar scenario of being accidentally locked in a store (or a vault, or an elevator, or whatever) overnight, with the added cruelty of being confined to a small, claustrophobic space — the chair lift — even though there is a world of open air around them. It’s like floating on a tiny raft in the middle of the ocean, dying of thirst in spite of all that water. (Speaking of which, “Frozen’s” premise recalls “Open Water,” where the married couple was accidentally left behind by their scuba-diving group. Someone in “Frozen” mentions shark attacks, which I assume is a reference to that.)

To an extent, things transpire according to the usual pattern. First there is irritation over the inconvenience, then fear and panic as they realize they’re trapped, then the morbid humor, the blaming, the turning on each other, and so forth. The scenes between the suspense sequences, where the three have nothing to do but talk, are passable but nothing special. When you have just three actors confined to one small location, their dialogue and their charisma have to sizzle to hold the audience’s attention. Bell, Ashmore, and Zegers are good, and admirably committed to what cannot have been a pleasant shoot (everything was filmed on location in Park City, Utah), but the film can’t survive with them alone.

Luckily, Green also has some excellent ideas about how to torment his characters. What can he do with three people stuck on a ski lift? You’d be surprised. Think about the possible means of escape. Then think about what could go wrong. Then think about it for a hundred years and I bet you don’t come up with the details Green does.

And that’s what makes “Frozen” work. Yes, the talking parts are only average; yes, the acting is solid but unremarkable; yes, the premise is simple. That’s why it’s all the more impressive that Green can spin it into a 90-minute film with several genuinely thrilling or horrific moments.

B- (1 hr., 31 min.; R, some harsh profanity, some very gruesome images and strong violence.)