Whirlpool: A Mystery by Barry Estabrook

When a fisherman hooks the corpse of real-estate developer Barron Quinell, the tranquility of the Adirondack summer ends. The task of discovering how Quinell died falls to Garwood Plunkett, a veteran cop more likely to rely on his instincts than on the manual.
Plunkett finds himself sucked into a vortex of deceit, hate, and greed that threatens to undermine everything he stands for, sweeping him from upstate New York's mountains to Manhattan's mean streets.
Meanwhile, Quinell's beautiful widow has hatched a scheme of her own, one that involves Plunkett, and that could buy them both happiness, or cost them their freedom - and their lives.