Logan Reynolds and his friends were excited for their spring break trip. A break from college and the cold Midwest weather, lying on the beach, and partying with friends. The simple road trip turns into much more than they bargained for when they decide to stop for a tour of Mammoth Cave.

Instead of relaxing in the sun, they find themselves looking for a missing friend in the dark cave system. When they emerge from the cave back into the open air, they realize that they are no longer in their own world.

They must learn to navigate this new realm and face its dangers together, but they are soon drawn into a fight for their lives against dark forces that none of them had ever expected. Cutoff from any outside help, the friends must use whatever tools they can to fight off their enemy and find a way back home, or they will be lost forever.