It is a dark and very stormy night as the novel opens, for a terrible gale howls around the professor's rambling but solidly built house, twelve miles from the nearest village. The entire countryside is gripped in terror after local girls have been murdered, and once darkness falls few people venture abroad. The tension increases after every chapter as the creepy plot hinges on efforts by those in his house to protect themselves and each other during a long and extremely stressful night.

After learning of another murder committed not far from the house, Professor Warren announces that as a matter of safety everyone in the house must stay locked inside that night. But just as he gives this order, there is a thunderous knocking at the front door...