Recommended reading - Some Must Watch, by Ethel Lina White (1933):

Some Must Watch

By Ethel Lina White.

Filmed as The Spiral Staircase (1946), directed by Robert Siodmak.

Paperback.

Published by Hinkler Books.

First published 1933.

ISBN 13: 9781743081167

ISBN10: 1743081162

ASIN: 1743081162

Description:

Film director Robert Siodmak took Some Must Watch as the inspiration for his classic, bone-chilling thriller, The Spiral Staircase. In this novel Helen Capel takes the position of lady-help in a remote country house owned by the Warren family. She learns that a murderer is on the loose. All four of his victims were young girls, and the last of these was strangled in a lonely house just five miles away. Helen feels safe inside the house, protected, but the maniac is closer than she fears.