Recommendations based on "The Math Inspectors Books 1-3"

The very first Famous Five adventure, featuring Julian, Dick, Anne, not forgetting tomboy George and her beloved dog, Timmy! There's a shipwreck off Kirrin Island! But where is the treasure? The Famous Five are on the trail - looking for clues - but they're not alone! Someone else has got the same idea. Time is running out for the Famous Five, who will follow the clues and get to the treasure first?

'Just as the Five are relaxing into the holidays, a burglar breaks into their uncle's study, searching for top-secret documents! And when George and Timmy mysteriously disappear, Julian, Dick, and Anne must track them down. Is the burglary linked to their disappearance--and what dangers must they overcome to find them?' -- Back cover.

Based on the Famous Five series by Enid Blyton, while spending a summer holiday camping on Kirrin Island, the Five become involved with jewel robbers.