After nine months of tumult, Sam Raintree is ready for some peace and quiet. A beach vacation with his boss and lover, Dr. Bo Broussard, promises to provide the serenity they both need. Without the usual tensions to distract them, Sam hopes he and Bo will be able to reconnect in a way they haven't in a while. Bo's business and his children command a great deal of his time, and Sam's looking forward to two weeks of Bo's undivided attention.

A new case for the Bay City Paranormal Investigations team puts a crimp in Sam's plans for a peaceful vacation. Fort Medina, a seventeenth-century citadel guarding the mouth of Mobile Bay, is less than five miles from their vacation beach house, and Bo invites the group to stay with them while investigating the place. Bo promises not to get involved, but Sam knows better. Sure enough, Bo joins the investigation on the second night, and talks Sam into doing the same.

Events take an alarming turn as Bo begins to change, his behavior becoming more erratic each day. Puzzled and frightened, Sam scrambles for an explanation while the man he loves turns into a volatile and unpredictable stranger. When the truth comes out, it may already be too late to save Bo from a force neither of them can control.