Broken Promises — Mark Sublette

In the first book in the Westin Blackwood Art Detective Mystery Series... A recently recovered $100,000,000 Willem de Kooning painting and a lost, thousand-year-old Mimbres pottery shard hold the unlikely keys to a missing Paul Gauguin masterpiece. One person knows how to unlock the thirty-five-year-old riddle — but art detective and bestselling self-help guru Westin Blackwood must traverse the gauntlet of childhood trauma to expose the guilty. Evil and death haunts the people involved, and they will do anything — including murder — to stop Blackwood from discovering their Broken Promises.