Hooked on Diamonds

Jed Namara had a corner office, award-winning ad campaigns, and a therapist who charged $300 an hour to look sadly at her notepad. He gave it all up for a battered straw hat, a leaking boat, and a tumbledown tuna cannery on a speck of Polynesian island with no roads, no electricity, no internet, and — as his one dead fish after a six-hour fishing trip suggested — no future.

But Goodway Island holds a secret. Somewhere in its caves, hidden since 1944, is a tin of Namara's Gold Brand Tuna. And...