Dead Water — C.A. Fletcher

In a chilling blend of folk horror and twisting suspense, this modern masterpiece depicts isolation and dread within a small island community.
  There's something in the water...   On the edge of the Northern Atlantic lies a remote island. The islanders are an outwardly harmonious community -- but all have their own secrets, some much darker than others. And when a strange disorder begins to infect them all, those secrets come to light.   Ferry service fails and contact with the mainland is lost. Rumors begin to swirl as a temporary inconvenience grows into nightmarish ordeal. The fabric of the once tight-knit island is unnervingly torn apart -- and whatever the cause, the question soon stops being how or why it happened, but who, if anyone, will survive.