Five highly qualified applicants interview for a coveted job with the Carcharias Corporation, a powerful conglomerate whose business practices are shrouded in mystery. On the night before the last round of interviews, they are all kidnapped and drugged. The next day, they wake up trapped together in a locked room without any hope of escape. Soon the true nature of their situation is revealed when they receive a phone call from the mysterious CEO of Carcharias, known only as The Employer. He informs them that they are about to experience the final interview, but it's not at all what they were expecting.

Spirit Lake is unusually deep. No diver has ever managed to find the bottom. When Dr. Amelia Brooks disappears during a deep-water dive, her three daughters travel home. They find themselves unable to let go and become drawn into the mysteries of the lake.