Mildred Davis published 12 suspense novels and one novella between 1948 and 1977. I think her best are The Room Upstairs, They Buried a Man and Walk Into Yesterday.
The novella Suicide Hour (Cosmopolitan magazine 1954) is a strangely charming miniature. It was never republished in book form. You can read or download this novella, free, at:
http://www.mildreddavis.com and get a complete bibliography.