When Venetian explorer Marco Polo (Gary Cooper) and his assistant, Binguccio (Ernest Truex), travel to Peking to locate Chinese treasures, they meet Emperor Kublai Khan (George Barbier) and his beautiful daughter, Princess Kukachin (Sigrid Gurie). The emperor's adviser, Ahmed (Basil Rathbone), sends Marco away from the palace in order to overthrow Kublai Khan and marry Kukachin. It is up to Marco to stop the plot, defeat the villain and win the hand of the princess.