Frozen

The director (whom I didn't know before this movie) gets to generate an authentic tension from a real suspense story: the panic gripping the trio is absolutely palpable, although the strong implausibility of no one having a cellphone is not that believable. The terror due to their predicament mounts minute by minute and is made genuine by showing a harsh environment and by imposing tension on each of the characters. The cast is not famous at all but the way the story is set and the three personalities are described keeps attention and tension high and strong. I recommend it also for the wonderful location (movie shot in Utah's Rockies).