The Strangers — Ed Falco

To inhabit the planet, they had to eliminate the Earth's indigenous human population. Trouble was, they missed a few. When Severn Price awakens during a violent storm to find his wife dead beside him in bed, he ventures out for help, only to find himself in the midst of an apocolypse that wipes out the Earth's human population—except for him and a few others who escape the purge. In the months that follow, they encounter aliens who look and behave like the humans they've replaced. Though the aliens who have repopulated Earth are peaceful, they bring with them something fierce and savage that the human survivors will have to face and defeat if they don't want to be the last of their species.