Nicolo Polo shows treasures from China and sends his son Marco Polo there with his assistant Binguccio. They sail from Venice, are shipwrecked, and cross the desert of Persia and the mountains of Tibet to China, to seek out Peking and the palace of China's ruler, Kublai Khan. The philosopher/fireworks-maker Chen Tsu is the first friend they make in the city, and invites them into his home for a meal of spaghetti. Children explode a fire-cracker, and Marco thinks it could be a weapon. Meanwhile, at the Palace, Ahmed, the Emperor's adviser, harboring dubious ambitions of his own, convinces Emperor Kublai Khan that his army of a million men can conquer Japan. Kublai Khan promises Princess Kukachin to the King of Persia. Marco, arriving at the palace, sees Kukachin praying for a handsome husband. Marco is granted an audience with the emperor at the same time as a group of ladies-in-waiting arrive; Kublai Khan lets Marco test the maidens to find out which are the most worthy. Marco tests them all with a question, and he sends off the ones who had incorrectly guessed the answer, as well as those who had told him the correct answer, retaining those saying they did not know. His reasoning behind this is that they are the perfect ladies-in-waiting, not overly intelligent, and honest. Kublai agrees and Marco immediately becomes a favored guest. Ahmed shows Marco his private tower with vultures and executes a spy via a trapdoor into a lion pit. Kukachin tells Marco that she is going to marry the King of Persia, but, having fallen in love with her, he shows her what a kiss is. A guard tells Ahmed, who vows to keep Marco out of the way. Ahmed then advises Kublai Khan to send Marco into the desert to spy on suspected rebels. Kukachin warns Marco of the deceiving Ahmed.
Contemporary reviews were mixed. Frank S. Nugent of The New York Times wrote that "we could never forget for a moment that it was all make-believe," referring to the actors' accents which were clearly inaccurate for the film's time and place. However, he went on, "it is amiable make-believe, rich in the outlandish pageantry Hollywood loves to manufacture, facilely narrated and enjoyably played." Variety called the film "a spectacular melodrama" and "an excellent vehicle for Cooper" and inaccurately predicted that it would be a box office hit. Film Daily called the film a "thrilling, romantic offering" and called Cooper an "excellent" choice for the role. Harrison's Reports found "Expert performances" and a romance "handled in good taste," but found that its appeal would be limited to "sophisticated audiences" because it was lacking in action. John Mosher of The New Yorker called the film "a big disappointment" and described the dialogue as having "the swing of a bad libretto." Motion Picture Daily praised the "lavish" production but said the title role would have been much better suited to Rudolph Valentino than Gary Cooper. The New York Sun wrote, "In spite of its elaborate settings and the presence of Gary Cooper, The Adventures of Marco Polo never quite lives up to its promises." In Italy, the fascist censors considered the film disrespectful to the eponymous hero and insisted on re-dubbing it to make the protagonist a Scotsman called MacBone Pan and releasing it under the title Uno scozzese alla corte del Gran Kan. The film was a box office flop, losing an estimated $700,000.
