Charlotte Armstrong (1905-1969) was an American poet, dramatist, and author of mystery short stories and novels. She was born and raised in the mining region of Michigan’s Upper Peninsula. After two years at the University of Wisconsin, she moved to New York and received a B.A. degree from Barnard in 1925. She had two plays produced on Broadway but neither was successful, so she turned to writing mystery fiction, beginning with Lay On, MacDuff (1942), the first of three detective novels featuring Professor MacDougal Duff.
It was with The Unsuspected that she achieved outstanding success and moved to Hollywood while it was being filmed. The 1947 Warner Brothers feature starred Claude Rains, Joan Caulfield, Audrey Totter, and Hurd Hatfield; it was directed by Michael Curtiz.