It's a hot, windy night in Los Angeles. The Santa Ana winds are blowing and the gusts carry the scent of smoke from distant brush fires. A bad night for running an errand, but the Speed-D-Mart probably carries what they need.
A group of tourists on a boat trip to a lake beneath the Earth's surface get trapped underground when their elevator fails. Without food, water or light they try to find an escape route, encountering nightmarish creatures in the dark.