A lone-wolf scientist sequestered in a mansion near a small desert town arouses the suspicion of the town's doctor when his lab assistant is found dead from a case of acromegaly which took only four days to develop. As the doctor investigates, aided by the scientist's new, and very female, assistant, they discover that, far worse, something much larger and hungrier than it ever should be, is devouring local cattle - and humans - in increasingly large quantities.
Rancher Rex Allen receives a summons from his uncle. an old time frontiersman, that he is in trouble. The uncle has been hired to lead a modern-day band of adventurers on a wagon train retracing the route taken by their ancestors 100 years ago. Before Rex can talk to his uncle, the uncle is murdered, and Rex sets out to find the killer and the motive by taking his uncle's place as the leader of the wagon train.
Larry Morgan, a private detective, is hired by a woman who wants Larry to trail her husband. The husband is murdered and, shortly afterwards, the wife is also killed. Larry shuffles through a long list of suspects before revealing the killer...
