The Spiral Staircase (1946) Directed 由 Robert Siodmak, is a psychological film noir starring Dorothy McGuire as the primary character, Helen.
It was adapted from a screenplay 由 Mel Dinelli and based on the Ethel Lina White novel 'Some Must Watch'. White also penned the original story that was used for Hitchcock’s film, The Lady Vanishes.
The movie is set primarily in a large Victorian house, Helen is a mute servant girl for the elderly bed-ridden Mrs. Warren (Ethel Barrymore). Also living in the mansion are the matriarch’s son Steve (Gordon Olivier), her stepson, Professor Albert Warren (George Brent), his assistant Blanche (Rhonda Fleming),  an abusive old nurse (Sarah Allgood) , Mrs. Oates the alcohol loving housekeeper (Elsa Lanchester) and her groundskeeper husband, Mr Oates (Rhys Williams) Also on the premises, the new Doctor in town, Dr Parry (Kent Smith). Events begin following the third murder of a disabled woman, Mrs Warren fears for Helens safety and urges her to leave town, before she is able to do so, one dark and stormy night, another murder takes place, this time within the house itself...
This movie is suspenseful with its use of evocative lighting, magnificent cinematography, and compelling performances 由 Dorothy McGuire as Helen, who displays a wide range of emotions even though she is mute following a trauma during childhood, Ethel Barrymore's performance earned her a nomination for best supporting actress as Mrs Warren.
Expressionist visuals akin to German cinema were allied to the latest sound effects to produce what became known as the `Old Dark House' thriller. The atmosphere is eerie and thrilling which permeates throughout this unsettling chiller. It also reminds me of the Giallo genre, containing many of the elements, yet it was produced decades prior. The first "true" giallo film is usually considered to be Mario Bava's The Girl Who Knew Too Much (1963)