An earlier user has already mentioned the similarity this plot (at least at first) bears to Sidney Howard's 'The Silver Cord', recently filmed with Laura Hope Crews repeating her Broadway role as a smothering mother coming between her mother's boy of a son and his new wife. In 'Double Door' too, an easily dominated young man is fought over by two stronger-willed females, mommy being replaced by a controlling, much older half-sister who also has her hapless sister under her thumb. In her only film appearance, Mary Morris recreates her stage role as the shrewish Victoria Van Brett, who the original publicity (and the film's credits) attempted to present as some sort of horror film ghoul - which extends into the film itself, since she wears heavy eye-shadow and is constantly lit from below - rather than the mercenary and manipulative domestic tyrant she actually is.
Anne Revere, who plays Victoria's downtrodden sister - also repeating her original Broadway role - shortly after this film was made was in the first Broadway production of Lilian Hellman's 'The Children's Hour'; so it's quite possible that Hellman saw her in 'Double Door', which would explain the similarity between the depiction of Victoria browbeating Caroline into submission and the powerful scenes preserved for posterity in William Wyler's 1936 film version of 'The Children's Hour', 'These Three', in which Bonita Granville coerces Marcia Mae Jones into backing up her malicious lies. Another much later film also anticipated by 'Double Door' is 'Panic Room', as becomes apparent when the meaning of the film's title is eventually explained.
Anne Revere, who plays Victoria's downtrodden sister - also repeating her original Broadway role - shortly after this film was made was in the first Broadway production of Lilian Hellman's 'The Children's Hour'; so it's quite possible that Hellman saw her in 'Double Door', which would explain the similarity between the depiction of Victoria browbeating Caroline into submission and the powerful scenes preserved for posterity in William Wyler's 1936 film version of 'The Children's Hour', 'These Three', in which Bonita Granville coerces Marcia Mae Jones into backing up her malicious lies. Another much later film also anticipated by 'Double Door' is 'Panic Room', as becomes apparent when the meaning of the film's title is eventually explained.