H.M.S. Surprise clears the decks for action and gives the people what they want, a straight-forward ripping sea yarn with lots and lots of action. Aubrey has got a proper ship, the elderly frigate Surprise, where he served as a midshipman. While a trick of the pen has erased his fortune for capturing the Spanish treasure fleet at the end of the last book, since England and Spain were not yet at war, any command is a good one, and a swift frigate is better than most.

Jack has to rescue Dr. Maturin from Port Mahon, where he has been captured as a spy and is being tortured by Napoleon's intelligence service, and then it is off to India, carrying a royal envoy to a sultanate in Malaysia. There's lyrical descriptions of the open sea, Maturin does his naturalist thing along Brazil (leading to one of the best lines in the books, "Jack, you have debauched my sloth!"), and then to Bombay, where the adventuress Diana Villers is living with the wealthy Mr. Canning.

On the return journey, there is some great action, as Aubrey leads a fleet of Indiamen against a French flotilla containing a ship of line, a deadly ruse relying on the bravery of civilian merchants to delay and then overwhelm the French with numbers while at a great individual inferiority.

And then Maturin fights a duel with Canning over Diana, and has to operate on himself to take the ball out! But all's well that ends well.