London, 1933: An amateur dowsing team searching the Thames for precious metals unearths the body of a young woman with a priceless coin in her mouth. The case falls on Scotland Yard Assistant Commissioner Joe Sandilands, but he has another, very high-profile assignment. London is hosting a massive economic conference to address the global Depression, and political tensions run high as world leaders stand either with or against a rapidly militarizing Germany. Sandilands is to protect visiting American senator Cornelius Kingstone throughout the conference. But a when a series of bizarre coincidences links the riverbank body to the senator, Joe realizes that Kingstone is caught up in a dangerous game that might cost not just one but thousands of lives.