This is book eleven in the Aubrey/Maturin series. Captain Aubrey, ashore after a successful cruise, is persuaded by a casual acquaintance to make certain investments in the City. This innocent decision ensnares him in the London criminal underground and in government espionage - the province of his friend Stephen Maturin. This dark tale is a fitting backdrop to the brilliant characterization and sparkling dialogue which marks O'Brian's style.