The journalist Alan Foster makes a bet than he can spend one night at the haunted Blackwood Castle. As he learns, the rumors of ghosts at the castle are indeed true. On All Soul's Eve the ghosts of the castle search for blood to tide them over for another year. In the castle Foster meet and fall in love with Elizabeth Blackwood
On leave in a shore side town, Johnny becomes interested in a young dark haired woman. They meet and he learns that she plays a mermaid in the local carnival. After strange occurrences, Johnny begins to believe that she may actually be a real mermaid that habitually kills during the cycle of the full moon.
Peter Plunkett's Irish castle, turned hotel is about to be repossessed, he decides ghosts would attract more Tourists. The trouble begins when a bus load of American tourists arrive. Among them, the daughter of the man who holds the mortgage and a paranormal psychologist and his family. When the real ghosts of castle get angry and decide to take a hand in things will they all survive Hallowee