Dink and his friends unearth the mysterious truth behind the envelopes incorrectly delivered to his house.

While learning detective skills at a sleep-away camp, Dink and his friends undercover a real mystery involving stolen paintings.

Dink and his friends meet an exchange student, Sammi, who is actually the prince of an island country, hiding from those enemies who have kidnapped his parents and who may be after him as well.

Dink, Josh, and Ruth Rose investigate the disappearance of a valuable racehorse that Dink's uncle and his friend, Forest Evans, have just bought and entered in a race at Saratoga.

While visiting Wallis's castle, Dink and his friends investigate strange noises that lead them to a dangerous secret.

Ten-year-old Cam, possessor of a photographic memory, and her friend Eric investigate what seems to be a brief appearance of UFOs.

Fifth-grader "Encyclopedia" Leroy Brown solves ten mysteries and, by putting the solutions at the back of the book, challenges the reader to do the same.

Timber wolves, a Rocky Mountain blizzard, and a mine cave-in are only a few of the perils Frank and Joe Hardy encounter during their search for the principal members of a notorious gang responsible for a payroll robbery. In the old Montana mining camp of Lucky Lode, the young detectives puzzle over a series of mysterious events. A piano-playing ghost haunts the long-abandoned dance hall. Eerie blue lights flash from the hilltop cemetery in the dark...