In the early 1800s, the British Navy stands as the only bulwark against the militant fanaticism of Napoleonic France. Jack Aubrey, a brilliant and experienced officer, has been struck off the list of post-captains for a crime he has not committed. His old friend Stephen Maturin, usually acting as the ship's surgeon to cover his activities on behalf of British intelligence, has bought for Aubrey his old ship, the Surprise, to command as a privateer. Together they sail on a desperate mission against the French which, if successful, may redeem Aubrey from the private hell of his disgrace.