During
World War II, Flash Gordon is on a mission in Warsaw, which is suffering heavy bombing. He arrives too late and his contact, who is near death, says he has a message for Doctor Zarkov, but can utter only one word, "Mongo", before he dies. Flash travels to find Zarkov and meets feisty 'girl reporter' Dale Arden, also on her way to interview him. They are bombarded by meteorites, which damage their plane and force them to bail out. On the ground they flee lava flows, and find a secret cave and a rocket ship. Doctor Zarkov, having no time for introductions, ushers them on board and they blast off. When safely in flight, he explains he is on a mission to the
wandering planet Mongo to convince their leaders to call off their attack on Earth (by force if necessary, using a gravity weapon of his own invention). For their part, Flash and Dale agree to help him. Before they can make contact, hostile ships shoot them down, and they make a crash landing. After barely surviving attack by two clashing dinosaurs, they are captured by animalistic savages and dragged to a giant idol to be sacrificed. They barely escape to the outside, where they meet the virtuous King Thun of the Lion Men and help him escape Amazonian hunters led by
Princess Aura. Flash and company are forced into war against Mongo's leader and Aura's father, the maniacal
Emperor Ming, and his robotic army of metal men. To help their cause, the heroes lead an alliance formed from freedom fighters led by King Thun, as well as Prince Barin of Arboria; and King Vultan of the Hawkmen. Thun explains Ming is too clever to conquer Earth by force alone, and that he would use the Mongo strategy of 'separate and attack' which Flash notes is the same as the Earth expression "divide and conquer". Ming reveals he has secretly given military technology to
Hitler, leader of the
Nazi Party. Ming sends his Mole Men to attack the kingdom of Arboria by destroying the roots of the trees of the forested land which provides camouflage. Thanks to Zarkov warning Flash and friends, the attack is repulsed and Flash and his allies use the captured drilling machine to attack Ming's palace. They are overwhelmed by Ming's forces, but Prince Barin insists on his right to a trial by strength. With a flaming sword and ion blaster in hand, Ming duels against Flash in an epic fight. However, Ming turns out only to be a android imposter and the real Ming escapes. With only seconds before Mongo collides with Earth, Flash damages the planet's drive mechanism on Zarkov's advice. With that move making Mongo safely go off course with no way to return to Earth, Flash tells Dale that they have nothing to regret since they are together on a new home of wondrous adventure. ==Cast==