Don't Bother to Knock is a 1952 American psychological thriller starring Richard Widmark and Marilyn Monroe and directed by Roy Ward Baker.

Monroe is featured as a disturbed babysitter watching a child at the same New York hotel where a pilot, played by Widmark, is staying.

Jed has checked in at the same hotel and approaches her; she explains that she sees no future with him because his coldness with people shows he "lacks an understanding heart".

Meanwhile, elevator operator Eddie introduces his reticent niece, Nell Forbes, to guests Peter and Ruth Jones as a babysitter for their daughter Bunny.

Seeing the striking young Nell from his room directly across an air shaft, Jed calls her on the house phone; alternately curious and put-off, she rebuffs his aggressive advances.

Jed snatches Bunny away, but the incident is witnessed by long-term hotel resident (and notorious busybody) Emma Ballew.

Irate that Nell is still wearing Ruth's things, Eddie orders her to change clothes, then harshly rubs off her lipstick.

Eddie explains that Nell had spent the previous three years in an Oregon mental institution following her suicide attempt, but was supposed to have been cured.

The reviewer for the New York Post was generally pleased with the film's individual performances, but panned its plot and structure.

He described Monroe as “surprisingly good”, and Widmark “terse, decisive and efficient, in veteran pilot style.” Of the work's direction, plot, and portrayals he wrote: “The picture’s suspense sequences are fairly effective both in gradual build-up and climaxes, but the conclusion, implying that all this had taken place merely to awake Widmark to his love for the singer, reduces the film to trifling proportions.

Only characterizations and the psychotic continuities lend it temporary semblance of solidity.”[2] The Albany Times-Union film critic was unenthusiastic: “Having whooped the undeniable physical assets of Marilyn Monroe from the rooftops, her home studio seems bent now upon telling the world that its blond property is also geared for heavy dramatic acting.

Why not just let her just be Marilyn Monroe, instead of a psychotic menace?....Miss Monroe walks through the picture as if she had been hit on the head….The action, transpiring entirely in the hotel, never gets higher than the eighth floor…..The picture has a brunette stranger, Ann Bancroft, as a nightclub songstress who jilts Widmark, takes him back the same evening.

Not sensational—but neither is she psychotic.”[3] The film's reputation has improved since its release, with many modern critics considering Monroe's performance as initially underrated.

He wrote, "Wacko psychological thriller, set entirely in a NYC hotel, and helmed without urgency by Roy Ward Baker (The Vault of Horror/Asylum/Scars of Dracula).