The book tells about the adventures of the detective trio. The first of them, the unrivaled leader of the company, is Mark Larkin, and his main tool is his sharp mind. The second, his sister Pamela or simply Pam, has first-class attentiveness. The third is Tim Wise, and his short stature makes up for the lion's share of courage. This time they are looking for jewelry stolen from a jewelry store and solving the puzzle of an old pirate.