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

The three investigators, attempting to rescue a beached whale, end up searching for sunken treasure.

The Three Investigators are assisted by a Greek youth as they search for clues to a mysterious thief on an island once inhabited by pirates.