The Nore and Spithead mutinies intervene to upset the course of Delancey's career. He devises an original legal defence in the court martial of a fellow officer accused of murder, and acquits himself well, but falls afoul of the naval establishment and is passed over in the general promotion of all in his rank after the victory at Camperdown.

With his Royal Navy commission in hand, Richard Delancey is posted to Gibralter to command the sloop Merlin for convoy protection in the Mediterranean.

Napoleon is planning to invade England. Rumors circulate of vessels driven by steam engines, of new explosive devices, and most perplexing and sinister a warcraft capable of travelilng underwater. It will take all of Delancey's skill and courage to confront the threat.

In this final book in the Richard Delancy series, Delancy's new command of the frigate Laura takes him to the East Indies.