While visiting the seaport town of Ragged Cove, Massachusetts, the Alden children find the ship's log of the Flying Cloud, shipwrecked in 1869, supposedly during a mutiny.
While their family is away, Harold and Chester, a dog and a cat, are boarded at Chateau Bow-Wow where Chester becomes increasingly alarmed by the strange behavior of his fellow guests and the sudden disappearance of one of them.
Anthony Monday and Miss Eells recover a magic lamp that was stolen from a warlock's tomb and is spreading evil to further the wicked ends of the thief.