Secret Beyond the Door (1947) on Netflix

Plot summary

Celia Barrett, a New York heiress, is engaged to her lawyer, Bob Dwight. She travels to Mexico with a friend, Edith Potter, and there meets Mark Lamphere, an American architect, and marries him. On their honeymoon she locks him out as a joke; he turns cold and leaves, saying business calls him home. Days later she reaches Levender Falls, where Mark's sister Caroline takes her to Blade's Creek. Celia learns that Mark has a teenaged son, David, and that he was widowed. Caroline and Mark's secretary, Miss Robey, look after the boy. Caroline hints that Mark had a hand in his first wife Eleanor's death, and David says his father killed her. At a party Mark shows six rooms he built, each recreating a notorious murder of a woman. A seventh room stays locked.