Night of the Saucers, by Eando Binder (epub/Kindle/pdf)
It was Earth's darkest hour. Weak, backward, prey to attack, it could only be saved by the Vigilantes. Sci-fi writer Thane Smith and his beautiful, adored wife had the task of discrediting UFO stories. But how can they -- after they run up against a playboy-monster who could only have been created by an alien race?