A science fiction writer is transformed into a Martian, and he figures out that real Martians are observing him to test how they can survive on Earth, so he tricks them into believing that they could not.
The Zaxians, a friendly alien race, send a spaceship to Earth as a gift, and the astronaut that is chosen to pilot it ends up saving the Zaxians from a hostile invasion.
An alien invasion force hides in a canyon that is a tourist attraction, but a determined tourist finds them in spite of their efforts and helps to drive them off Earth.