Twelve-year old Johnny Dixon and his friend Professor Childermass look for the hidden will left by an eccentric cereal tycoon who wished to make life difficult for his heirs after his own death by suicide.

While thirteen-year-old Johnny Dixon lies dying, possessed by an evil spirit, his friends, an elderly professor and a schoolmate, try to find some way to free him.

Johnny Dixon and Professor Childermass discover a trolley which transports them back to Constantinople in 1453 as the Turks are invading the Byzantine Empire.

When Father Higgins disappears, Johnny Dixon and Professor Childermass discover disturbing clues which lead them to England and an encounter with a long-dead knight.

By donating a box full of strange objects, Professor Childermass gets his young friend Johnny Dixon a summer job at the Gudge Museum. Everything seems okay as Johnny mops the floors and dusts the artifacts. That is, until a sinister man named Mattheus Mergal shows up looking for the one item the professor held back to keep safe-a wooden hand carved by the evil wizard Esdrias Blackleash. If Mergal gets the hand, he'll be able to bring back his long-dead...