In the future world of 1980 the United States Air Force's Space Exploration Wing has bases on the moon and is on the eve of a mission to Mars. When yet another of their Pegasus spacecraft with its two-member crew mysteriously disappears leading to rumors among the ranks of "space monsters" and "phantom planets", Mars mission pilot Captain Frank Chapman and his navigator Lt. Ray Makonnen are sent to investigate in their own Pegasus craft.
In 1965, a series of mysterious and devastating incidents are happening on Earth. These incidents range from a railroad bridge levitated off the ground causing a train wreck in Japan; an ocean liner lifted out of the Panama Canal by a waterspout, destroying it; severe flooding in Venice, Italy; and the destruction of the J-SS3 space station.
U. S. Navy Cmdr. Charles "Chuck" Prescott (Thompson) is not sure if his brother, Lt. Dan Prescott (Edwards), is the right choice for piloting the rocket powered Y-13 to very high altitude. Capt. Ben Richards (Ayres) of the Air Force Space Command insists that Dan is their best pilot, even though when piloting the Y-12 into the ionosphere, he began experiencing flight difficulties. Upon landing, Dan broke flight regulations by going to see his girlfriend (Landi), rather than immediately filing his flight report. Despite these concerns, Capt. Richards insists that Dan pilot the Y-13 after a thorough check-out and briefing by Dr. Paul von Essen ([Jaffe).
In the 23rd century, to discover the fate of an expedition sent 20 years earlier, starship C-57D reaches the distant planet Altair IV. Dr. Edward Morbius (Walter Pidgeon), one of the expedition's scientists, contacts the starship. He states no assistance is required, warning the Earth ship away, saying he cannot guarantee their safety. Commander John Adams (Leslie Nielsen) insists on landing.
The Planet of Peril
The planet Mongo is on a collision course with Earth. Dr. Alexis Zarkov takes off in a rocket ship to Mongo, with Flash Gordon and Dale Arden as his assistants. They find that the planet is ruled by the cruel Emperor Ming, who lusts after Dale and sends Flash to fight in the arena. Ming's daughter, Princess Aura, tries to spare Flash's life.