Thirteen-year-old Nathaniel, aided by the famous magician Harry Houdini, plots to unmask a phony spirit advisor attempting to relieve the boy's great-aunt of her fortune.

While traveling to England with his mother and great-aunt on the ocean liner Lusitania in 1911, thirteen-year-old Nate, delighted to find that the Houdinis are also on board, finds himself involved in another dangerous adventure as he and Houdini try to find the man responsible for attempting to assassinate another passenger--President Theodore Roosevelt.