The ocean-side community of Hidden Beach, Florida, is under attack. A series of murders has the police scrambling to find the killer, and as the body count rises, they narrow their search to Henry Watchman, pastor of Hidden Beach Community Church. Though the pastor denies having any part in the murders, he and his wife, Jenna, are hiding a terrible secret.

Vincent Anderson, a young detective on the force, is bending his time and effort to catching the pastor -but the murders continue. And behind it all, a shadowy force rises from the ocean's depths. Though unseen, it pushes men and women to the brink of ruin. If not stopped, the sinister force will swamp many of Hidden Beach's citizens in a Demon Undertow.