Chris and the crew of the Pioneer encounter radioactive, crystalline men in the Green Nebula and foil a plot to steal the Nebula's radium.; Darwin meets a young actress who has accidentally bathed in the Fountain of Youth.; A scientist uses a hydrogen bomb to cause rain, resulting in a world-wide flood. He uses a second bomb to save mankind.; A story about a seat-of-the pants, first landing on the moon.; A description of devices, events, and innovations predicated by Wells in his fiction.