Jack and Jo combine their detecting skills with some old fashioned fishing expertise to investigate an allegation of cheating during the annual Mt. Thomas fishing competition. Compo Hayes, known well to the police as a highly seasoned scam merchant, just happens to win the competition which is worth a cool $10,000 gold ingot, and an incensed fellow angler makes an official protest. But a dispute over a fish rapidly escalates into something far more serious when the gold ingot prize is stolen. Was there a fish switch? And who would viciously bash the security guard to get the ingot? Although it is Jack's angling experience which puts them on track to solve the case, Jo has a surprise for him up her sleeve.