"I watched the victim convulse as if struck by lightning. Smoke rose from his scorched hair. Blood geysered from his carotid artery and splattered the brick wall. I ran away-I must warn everybody." * * * Charles Evans, a New York City architect, and TV reporter Dora Reeves learn that unforeseen consequences of advanced technology have forced an alien race of incorporeal beings in a parallel universe to search for a new world. The aliens discover Earth. Although lacking weapons, they devise means to infiltrate human society in order to eradicate the people of Earth, by utilizing humans'...