Chief Inspector Strock gets the tough cases. When a volcano suddenly appears to threaten mountain towns of North Carolina amid the non-volcanic Blue Ridge Mountains, Strock is posted to determine the danger. When an automobile race in Wisconsin is interrupted by the unexpected appearance of a vehicle traveling at multiples of the top speed of the entrants, Strock is consulted. When an odd-shaped boat is sighted moving at impossible speeds off the New England coast, Stock and his boss begin to wonder if the incidents are related. And when Strock gets a hand-lettered note warning him to abandon his investigation, on pain of death, he is intrigued rather than deterred.