As Professor Sebastian Warren battens down the shutters and locks all the doors of their isolated country house, the eight occupants start to feel safe. Somewhere outside lurks a murderer of young girls, the latest only an earshot away. Is there really safety in numbers and what happens when their numbers start to dwindle? The novel was adapted for a radio production starring Helen Hayes, and in 1946 director Robert Siodmak took it to the big screen, under the title The Spiral Staircase.