Three young sleuths investigate the disappearance of a caveman's bones from a museum and uncover skulduggery at a science foundation.

Searching for a legendary pirate treasure, the three investigators find a band of modern day pirates.

A wallet dropped by a scar-faced beggar sets the three investigators on the trail of bank robbers.

A hidden treasure is suspected, some criminals with a plan show up, and the Three Investigators end up right in the middle.

The crime-fighting trio races against time to recover a priceless Alvaro family heirloom before their friends lose everything. Reprint.