The Purple Monster Strikes

A Martian spacecraft crash-lands near the observatory of Cyrus Layton, designer of Earths first spaceship. The survivor, forerunner of an invasion, can assume the form of any earthman. Calling himself the purple monster, the humanoid invader sets about gaining control of Laytons rocket project. Opposing him is former Secret Service man Craig Foster who, episode by episode, tries to thwart the monsters attempts to acquire rocket components. Will Craig ever suspect that his closest associate is really the monster?