Gabriel Allon investigates the murder of the former princess of England and enlists the help of Christopher Keller, a British commando turned professional assassin, to track down master bomb maker Eamon Quinn.

The target is royal; the game is revenge. Stretched topless upon the foredeck, drink in hand, her flawless skin baking in the sun, was the most famous woman in the world. And one deck below, preparing an appetizer of tuna tartare, cucumber, and pineapple, was the man who was going to kill her. But when a bomb explodes aboard her holiday yacht, British intelligence turns to one man to track down her killer: legendary spy and assassin Gabriel Allon.