After a group of biologists discovers a huge network of unexplored caves in Romania and, believing it to be an undisturbed eco-system that has produced a new species, they hire the best American team of underwater cave explorers in the world. While exploring deeper into the underwater caves, a rockslide blocks their exit, and they soon discover a larger carnivorous creature has added them to its food chain.
An Army veteran assembles a team of bodyguards to protect a former boxer. Complications arise when the boxer suspects his sister may be romantically involved with the bodyguard.
A young woman in Paris goes to a party in the enormous labyrinth of limestone tunnels beneath Paris. When she becomes separated from her friends, she is convinced something is chasing her through the dark tunnels.
