The Franchise Affair is a 1951 film closely based on Josephine Tey's excellent novel. It offers a crime story, but not a murder mystery. Rather, the puzzle is based on the real life Elizabeth Canning case. A girl accuses a woman and her grumpy old mother of kidnapping her, and forcing her to become their servant. The accused women call in a local solicitor, Robert Blair, to defend them.
It's a low-key premise, one which is, I think, better suited to a book than a film, because it's not an obviously dramatic situation, despite a courtroom scene (in which the key twist comes rather out of the blue - a flaw in the writing). That said, I found The Franchise Affair to be a good example of the "well-make" post-war British film, with good performances from an excellent cast who make the most of the story's potential.
Michael Denison plays Blair, one of those small town solicitors from the Good Old Days, when you could take on a client without worrying about letters of engagement, or compliance with the anti money laundering legislation. Nor does he have to bother with computerised time recording, or targets for chargeable hours, lucky fellow. This freedom enables him to take on a case for which he's not really equipped in terms of experience. But determination sees him through.
Marion Sharp is played by Dulcie Gray, who was Denison's wife in real life. She was also a writer of mystery stories. As it happens, I've recently bought one of her books, and look forward to reading it. The remaining cast includes such future stars as Kenneth More (later Father Brown) and Patrick Troughton (a future Doctor Who). All in all, I enjoyed this film. I watched it the day after watching the much more dramatic The Shining. But in its quiet and unambitious way, it was equally entertaining.