The comic strip follows the adventures of Flash Gordon, a handsome polo player and Yale graduate, and his companions Dale Arden and Dr. Hans Zarkov. The story begins with Earth bombarded by fiery meteors. Dr. Zarkov believes the meteors are from outer space, and invents a rocket ship to locate their place of origin. Half mad, he kidnaps Flash and Dale, and the three travel to the planet Mongo, where they discover that the meteors are weapons devised by Ming the Merciless, evil ruler of Mongo.
For many years, the three companions adventure on Mongo, traveling to the forest kingdom of Arboria, ruled by Prince Barin; the ice kingdom of Frigia, ruled by Queen Fria; the jungle kingdom of Tropica, ruled by Queen Desira; the undersea kingdom of the Shark Men, ruled by King Kala; and the flying city of the Hawkmen, ruled by Prince Vultan. They are joined in several early adventures by Prince Thun of the Lion Men.
After years of adventures on Mongo, with only a short break during World War II to fight the Red Sword invaders back on Earth, the three heroes travel to other planets. They then make Earth their home base, and Flash joins the World Space Council as a pilot and explorer. At this point, the stories are set ten years in the future, so that a 1960 story from the strip will be set in the future year 1970, when our space program has reached most of the planets of our own Solar System.
The long story of the Skorpii War takes Flash to other star systems, using faster than light starships. Flash and his friends also frequently return to Mongo, where Ming has been overthrown and Prince Barin, married to Ming's daughter Princess Aura, has established a peaceful rule (except for frequent revolts led by Ming or by one of his many descendants).