Since his deaths, Trevor Hall couldn't help but feel he was different. The events that led to his demise are a mystery, but when the voices start, he knows he must solve the puzzle, or go insane.

Compelled by the array of spirits occupying his mind, Trevor struggles to understand what has happened to him. As his memory clears, he discovers the three entities possessing him have come to prevent other spirits who have already crossed, from taking control of humankind and reclaiming their lives.

As more entities find and possess human hosts, Trevor's task becomes more difficult. With the fate of humanity at stake, Trevor and his new personalities must find a way to block the portal and send the existing spirits back to the other side before their numbers grow beyond containment.