The expedition takes Jack Aubrey to the unusual landscapes and scents of the Indian subcontinent - where he seizes a gunboat and storms a nest of enemy spies who are holding prisoner his friend Stephen Maturin, ship's doctor, musician and secret agent. Then he receives the commander of a frigate, the Surprise, with the mission of conveying an ambassador of Her Britannic Majesty to India. Drifting to the coast of Brazil, descending towards the tip of Africa with passage of storms under the Cape of Good Hope, then ascending towards Asia. Scurvy epidemic, tornadoes and monsoons... Dramatic or tragicomic adventures follow one another, on board and at stopovers, in increasingly exotic lands.