Nelson - already a hero after his defeat of the French at the Battle of the Nile -- returns to London in 1800 to the adulation of the public and the suspicions of his wife. Aware of rumors about her husband and Lady Hamilton, Lady Nelson feels her man and their marriage slipping away.

In 1798, with Naples beset by revolutionaries and threatened by the advancing French Army, British envoy Sir William Hamilton sees Nelson as the kingdom's only salvation. But the aging diplomat also observes his vivacious, much younger wife's obvious attraction to the admiral - as well as a distinctly ungentlemanly side to Nelson's character.

In 1805, Thomas Hardy - captain of Nelson's flagship, Victory - visits his commander's country estate to help plan a final blow to the French fleet. There, the straitlaced officer is shocked by Nelson's social-climbing new friends and vulgar new wife, precipitating a confrontation between the captain and his commander.