Johnny Dixon, Fergie and Professor Childermass comply with a strange will left by the Professor's brother, which requires them to spend the summer at a desolate estate where they encounter a madman bent on destroying the world.
When they discover mysterious hieroglyphics on the back of a photograph encased in an old locket, the three Shadow Beach Treasure Hounds determine to find out what they mean.
When the Aldens go to the Pickering Natural History Museum to assist with the opening of a dinosaur exhibit, their work is hampered by a series of mysterious happenings.
When the terrifying headless demon of Kimbu Tacka threatens an archaelogical expedition in the South American jungle, Miss Mallard uses her detective skills to unravel the clues and uncover the true villain.
Fifth-grader Cam uses her photographic memory, with help from her friend Eric and his twin sisters, to solve the mystery of Poochie, a famous canine television star.