When the body of Shadow Valley resident Dason Williams is discovered in his mother's basement it appears to be a clear-cut case of suicide, but seasoned paranormal investigator Maureen Keslyn knows otherwise. A photograph on the dead man's wall links him to a murdered teenage girl whose body bears the marks of a dangerous paranormal creature known as the Medusa.

Convinced that the Medusa is on a killing spree, Maureen joins forces with an unwieldy team--Jake, the local sheriff, Matt, the Shadow Valley Manor cook, and Sophronia, a teenage girl with an uncanny affinity for ghosts. The case is complicated by the ghost of Maureen's former partner who refuses to cross to the other side, and his much-too-alive daughter Jillian who shows up to claim her father's ashes--and take charge of the Manor.

With the life of one of their own in deadly peril, Maureen and the team enlist unlikely allies as they race to unravel a mystery that threatens not only the residents of the Manor, but all of Shadow Valley.