Captain Petroc Gray, commander of the ship-rigged sloop of war, HMS Kestrel, is drawn into diplomacy, intrigue, and espionage when he rescues the Freiherr von Dieffenbach and his family off the island of Rügen in the Baltic. The Freiherr is an important and valuable connection in the struggle to beat the Napoleonic Continental blockade of British trade, and his daughter, Silke, is a delightful young woman with a quick wit, brilliant intelligence, and a keen eye for observing the events unfolding around them. The ever-changing political alliances of the Northern European and Scandinavian states-war, sea battles, storms, death, and Napoleon's "hundred days" leading to the defeat at Waterloo—all conspire to frustrate Petroc's intention to seek Silke's hand in marriage, right to the last. But Petroc isn't one to be easily defeated, whether he is navigating the open seas or matters of the heart, and Silke stands bright and strong in his life like a beacon in a safe harbour.