A trip to Ireland to finish off the Robin Hood Treasure Tour had not sounded too bad to Ellen Allandale - until she discovered that it was to be made by ship and not by airplane. While her brother Carter gloated over the fact that he did not become seasick as she did, Ellen resigned herself to the trip. The treasure, locked away in a special cargo hold of the ship, seemed safe. How could anyone steal it in the middle of the ocean - only someone did, leaving Ellen, Carter, and Uncle Ruford stuck in an old mansion overlooking the ocean, until Scotland Yard solved the theft. But even there, mystery followed; the owner of "Seascape" believed her home to be haunted, and sought Ellen's help in discovering and eliminating the ghosts - a task to which Ellen reluctantly agreed. What awaited her, not even Ellen could have guessed.