Off the coast of Cape Cod, a Japanese bluefin tuna buyer is found dead on another man's boat, a harpoon shot through his chest. The dead man's grandfather, a Japanese fishing tycoon, seeks out part-time private investigator Aristotle "Soc" Socarides to find those responsible for his grandson's death. Soc is desirable because he's also a part-time fisherman; because the man also knows that Soc is deeply in need of funds to repair his dilapidated fishing boat, he knows Soc'll accept.

Soc can't shake an uneasy feeling about the way the old Japanese man found him and the way he persuaded Soc to take the job: "It was almost as if he knew me better than I knew myself." This realization should trigger a warning light in Soc's head. Maybe it does. But now Soc is curious. And he still needs the money.

What starts out as a simple inquiry into a young man's death to secure the peace of mind of an old man mushrooms into an excavation of the bluefin-fishing community. As Paul Kemprecos's Shamus Award-winning p.i. is about to find out, it is a small, close-knit but competitive group, where the fact that a single tuna has a ten- to twenty-thousand-dollar price tag may inspire men to do evil.