It is prior to the commencement of World War II, and Japan's fiendish Black Dragon Society is hatching an evil plot with the Nazis. They instruct a brilliant scientist, Dr. Melcher, to travel to Japan on a secret mission. There he operates on six Japanese conspirators, transforming them to resemble six American leaders. The actual leaders are murdered and replaced with their likeness and Dr. Melcher is condemned to a lifetime of imprisonment so the secret may die with him.
In the 22nd Century, Ray Peterson, reporter for the Interplanetary News, is assigned to write a story aboard a space station. Tension mounts between Peterson and the station's ommander, who think he's in the way, but has orders to leave him alone. Errant spaceship, Alpha Two enters the solar system and its photon generators are radiating enough heat to destroy Earth as it approaches. It falls to Peterson to try to figure out a way to enter the spaceship, disarm the generators, and escape before suffocating.
Spies discover that the Red Chinese have built a "doomsday machine" capable of destroying the surface of the Earth, and that they plan to use it within a matter of days. Meanwhile, Project Astra, a manned U.S. space mission to Venus, is in its final hours before launch when it is taken over by the military and nearly half of its all-male crew is replaced by women. The reason for this becomes apparent when, shortly after Astra leaves orbit, the Earth is completely destroyed in a global cataclysm! Is the human race doomed? What dangers and wonders await the crew of the Astra on their journey to Venus?
Ev, along with her husband, Harold, and their lawyer friend Martin, are scuba diving while on vacation in Puerto Rico. When they resurface, they gradually conclude that an unexplained, temporary interruption of oxygen has killed everyone on the island... maybe even the world.