A Japanese business tycoon mysteriously disappears and, soon after, a rare samurai sword is stolen from an art gallery. Suspecting a connection, the Hardy boys try to solve the mystery. Shortly after his arrival in the United States, a Japanese business tycoon mysteriously disappears. Then a valuable samurai sword, said to have belonged to the missing tycoon's family for generations, is stolen from an auction gallery in New York. Danger confronts them constantly as the Hardy Boys search for the solution to the puzzle.