Hornblower is looking forward to going to sea but a lot happens before he does so. Nelson's body has been brought home after Trafalgar and his state funeral is being planned; Hornblower is in charge of the naval procession up the Thames. Once the ceremony has been completed he is presented to the King, who assigns a young German prince to him as midshipman. Immediately after this, Maria gives birth to their second child, a daughter, but Hornblower has little time to spend with them; he has to make preparations to go to sea.
Hornblower's orders are that he is to take a Scottish engineer, together with some Ceylonese divers, to try to raise a treasure that was lost when a British ship sank in a bay on the coast of Turkey. Just before they sail the engineer fights a duel with the young prince's chamberlain, who is serving as the ship's doctor. The engineer is shot in the chest and seems certain to die, but Hornblower takes him anyway and orders the doctor to try to keep him alive long enough to supervise the salvage operation.
The salvage is technically difficult, involving the setting off of explosives at depth. Fortunately the engineer has now recovered sufficiently to supervise the process and most of the treasure is brought to the surface. Then a Turkish warship arrives in the bay and Hornblower is ordered to surrender the gold he has brought up. But he makes a daring escape by night past the guns of the coastal batteries and gets away.
At the end of the book Hornblower learns that he will be given command of a frigate. He returns to Portsmouth to take up his new post, but when he goes to give Maria the good news he finds that his young daughter is seriously ill, and when he touches her he realises it is smallpox.
There is, as usual, plenty of action, although we have to wait until the second half of the book to leave British waters. The technical details of how the treasure is recovered are well described; it would be interesting to know if anything of the kind was actually carried out by the British Navy at this period.