In 1798, the British Royal Navy withdrew from the Mediterranean to combat the threat of invasion at home. In their absence, rumors abound of a French Army gathering in the south of France under General Napoleon Bonaparte, and of a large fleet gathering to transport them. Alexander Clay and his ship, Titan, are sent to the Mediterranean to investigate. Clay verifies the troubling rumors but is unable to learn where the French fleet and the army will be heading. 

When Admiral Lord Nelson arrives from Britain with reinforcements, Clay and Titan join Nelson’s fleet heading for the south of France. But on their arrival, they discover Bonaparte’s fleet is gone, and Nelson, aware of the dangers of an ambitious and ruthless general, orders an all-out hunt for Bonaparte’s armies before it is too late. 

As the Titan searches for Napoleon’s forces, another threat has already gained passage on the ship. After engaging and destroying a Russian privateer, the crew capture a mysterious stranger, claiming to be an English sailor who has been serving from childhood on Barbary ships. Shortly after he joins the ship, there begins a rash of thefts, followed by the murder of another sailor. With the officers baffled as to who is behind this, it falls to Able Sedgwick, the Captain’s coxswain and the lower deck to solve the crimes.