They're the "alphabet sisters", Abigail, Bernice and Cecily, owners of the Cape Cod Inn where Murphy, his best friend Peter, and best enemy Ashley are staying while Murphy and Ashley's moms attend a conference. The old place is straight out of a horror movie -- and so is the sisters' ever-simmering sewer soup. But the real adventure begins when they discover ghosts on the beach, pirate maps in a creepy old cabin and half-burned papers with a plot to eliminate the three sisters! The kids think they know the killer -- but how can they catch him in time?
