Encyclopedia Brown, Idaville's ten-year-old "Sherlock Holmes, " solves ten mysteries.

Jim Qwilleran and his Siamese sleuths, Koko and Yum Yum, investigate the disappearance of a wealthy railroad buff in this mystery in the New York Times bestselling Cat Who series.
Floyd Trevelyan’s historic steam locomotive, newly restored, is the newest attraction in Moose County. But the excitement is eclipsed by shock when Trevelyan disappears—along with millions of investors’ dollars. Puzzled and suspicious,...

Ten brief cases allow the reader to match wits with ten-year-old crime-buster, Encyclopedia Brown, as he investigates such cases as whether a diary of George Washington's mother is authentic, or if a UFO picture supposedly taken by the army is real.

As Frank and Joe investigate the mysterious disappearance of a college professor, they stumble upon a baffling secret in a complex network of caves.

Thirteen-year-old Trixie Belden and her friends search for hidden treasure in a mysterious mansion owned by an old miser.

Nancy and her friends establish headquarters in a seaside yacht club to investigate strange happenings in a book store and the disappearance of a marble statue.