A sixteen-year-old farmhand is tricked into fighting in the Napoleonic Wars by the farmer for whom he works, who secretly substitutes him for the farmer's own son.
Jack Hoyton is only twelve years old when he enlists in the Royal Navy and is assigned to the HMS Defender. He learns about discipline and danger, and when the ship is betrayed by a spy, it is up to Jack to let the crew know that the Defender is headed into a trap!