March, 1914, is near the end of the high-season at Monte Carlo, a place teeming with international dignitaries, royalty, celebrities, and, not so incidentally, spies. Lily Turner, an ambitious young American, has taken a secretarial position to fund the budding detective agency she and a friend have established. Paul Newcastle is a con-artist and British expat who is about to age out of the game and needs a big score, soon. Their paths meet when they are conscripted into investigating events surrounding a death at the luxurious Hôtel de Paris. At first, they work separately in negotiating the evolving mysteries. A second murder and the arrival of Paul’s nephew ups the stakes to life-and-death. As the danger around them escalates, Lily and Paul are forced to rely upon one another even though neither trusts the other.
Along with a dash of romance and plentiful authentic locales, the story is served within a rich stew of the era’s political and social movements, including women’s rights, Irish nationalism, labor unrest, the rise of Socialism, the turmoil in Tsarist Russia, the revolutions in music and ballet, and the looming catastrophe of the First World War.