Frank Hardy has joined the Bayport fencing class, and although just a beginner, he's been selected to participate in a major tournament. But the competition is cutthroat-in more ways than one. He and his brother,Joe, who's coming along for the ride, will have to keep their swords sharp if they want to stay alive.
One of Frank's top rivals vanishes, and the boys suspect kidnapping. Their search leads them to the castle estate of a wealthy industrialist, sponsor of an elite-and deadly-fencing team. Doing battle with saber and samurai sword, the Hardys make a sinister discovery that could turn a single grudge match into a fight to the death.