Two young women, a young man, and a tween sister to one of the others go caving to find "Hopper," a missing archaeology professor that one of them likes. Hopper disappeared a couple days previously. Once inside, they discover that time doesn't behave normally in the cave. While I'd like to tell you more about the movie, that would probably step over into spoilers. The movie is ridiculous, but also goofy fun. Its origins as a meant-to-be "found footage" movie are clear, but happily they opted out of that idea and settled for steady and sane camera work. None of the actors are well known or particularly good, but they all do a good-enough job and are having fun. The ending is as absurd as the rest of the movie, but (for what little credit it's worth) it was nowhere near what I expected. Entertaining.