A present-day teenage couple, Mike Gardner and Jennifer Owens, are students on a training ship off the California coast. Defiant is a replica of a 19th century frigate. The ship is hit by a severe storm, and while the couple work on deck to furl a sail, lightning strikes the ship. Mike is knocked unconscious. As he comes to he realizes the ship is under fire. His first thought is terrorists, but he soon learns he's actually on a real British frigate, HMS Swift, the firing is from a French shore battery, it is 1805, and he has somehow taken over the body of one of the ship's midshipmen, Peter Southby. Based on his confusion and panic, the ship's doctor concludes that Mike (Peter) is suffering from amnesia. Jennifer is washed ashore on a French beach nearby. She is later rescued by Mike and the crew of Swift and eventually made the doctor's assistant. The mission of Swift is to watch for any French ships that try to run the British blockade of Brest. Mike is soon in action as part of an expedition in ship's boats to "cut-out" a French sloop-of-war anchored just inside Brest. He proves himself in hand-to-hand combat in the successful raid. Later Swift is engaged in a horrific battle with a French frigate. Swift captures the French ship and is sent to England for a lengthy refit. Once ashore, the two travel to the home of Mike's "parents," whom neither have met before. There, Jennifer learns she is now Catherine Devers, who is engaged to marry the politically powerful Lord Wolvington. She also learns that he owns slaves on his plantation in the U. S. Horrified, she vows to escape, with Mike's help, to someplace where Lord Wolvington and his men can never find them...