Set in a New York hotel with so much crime it needs an in-house detective, Don’t Bother to Knock follows Nell (Marilyn Monroe) who’s babysitting for the well-to-do Joneses (Lurene Tuttle and Jim Backus). Meanwhile pilot Jed (Richard Widmark) arrives to win back his  lounge singer girlfriend (Anne Bancroft). But when he sees Nell through the window he starts his descent towards a different runway.

This set-up sounds like a fairly typical romantic farce, but when Jed goes to Nell’s room to flirt while a distressed child (Donna Corcoran) lies awake in an adjoining room the mood begins to shift. Initially this appears to be the bizarre, selfish behaviour of a 1950s romantic comedy, but gradually we realise the scene, indeed the entire film, is not what it seems.

It shifts into a darker tale about a woman with a scarring past and deep mental health problems, abandoning any sense of comedy or romance for a tense and involving story. Monroe embodies the mood change in the film – her typically air-headed floozy making a smooth transition to a troubled and unstable person in a very sympathetic performance.

I love a film which subverts your expectations (see Million Dollar Baby) and Don’t Bother to Knock does just this, making for a gripping 75 minutes, and a great example of what Monroe can do in a more serious role.