1803: Just three years after his life was devastated by the loss of his fiancée, British Navy Lieutenant Neville Burton has returned to greater exploits in Jamaica. His new assignment as "Master and Commander" of the captured topsail schooner HMS Superieure had been rough so far. The ship's company, drawn from the dregs of the fleet, were only just now pulling together. A mutiny early on had sent the worst of them off to try their hand at being pirates of the Caribbean. Commanding a Royal Navy ship in the Napoleonic War is not Burton's only source of peril, however. His spymaster mentor has pressed on him the investigation of a possible spy. Fate intervenes when he meets the American Chester Stillwater. His grief only now subsiding, he has no intention of seeking an affair of the heart; but he discovers Stillwater's daughter, a beauty with an uncanny resemblance to his lost lover.
New romance will not be simple, however. Her disapproving father is the man Neville has been assigned to investigate as a suspected secret agent. Burton's desire to see Marion is first hindered by an irritating competitor who proposes a duel for Marion's honor, and then thwarted by the war-mongering Napoleon. When the Peace of 1802 is cast aside, England's war with France resumes. Neville's ship is ordered to join Admiral Nelson's squadron and return to Europe, and he must drop the games of intrigue and romance to join the war. Pure luck prevails: while Lt. Burton's ship is in London for repairs, he discovers that the headstrong Marion is also there, waiting for her chance to cross the Channel and sell Stillwater rum to the French Navy. Their dizzying dalliance is only a prelude to disaster. The competitor for Marion's hand makes his move at a clandestine meeting in Paris while Burton must sail to join Admiral Nelson's blockade at Cadiz, Spain. The naval engagement that follows is the Battle of Trafalgar, where Burton, now the captain of a frigate, fights his ship honorably, but is seriously injured. Burton finds himself recovering under the care of Mary, his now-widowed childhood sweetheart, and he receives news that Marion herself may be a spy. Can Burton pull himself up after yet another tragic love affair? Should he take up with Mary? Does the suspicion of Chester Stillwater have merit? Is Marion involved?