Ethel Lina White 
Spiral Staircase [EPUB ebook] 

Helen Capel takes the position of lady-help in a remote country house owned by the Warren family and, before long, 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.