While the City Sleeps is a 1956 Film Noir crime thriller directed by Fritz Lang and featuring a star-studded cast. It was adapted from the 1953 novel The Bloody Spur by Charles Einstein, itself loosely based on the case of real-life murderer William Heirens.
New York City media mogul Amos Kyne (Robert Warwick) dies, leaving his empire to his playboy son, Walter (Vincent Price, not yet typecast as a creepy horror movie star). Walter, wanting to change personnel without getting his hands dirty, creates a high-ranking position and makes his top three men compete for it. The catch is that they have to try and solve the sensationalist case of the so-called Lipstick Murderer. There's Mark Loving (George Sanders), Jon Griffith (Thomas Mitchell), and Harry Kritzner (James Craig), ready to vie for the position. Loving has Mildred (Ida Lupino), a reporter and occasional lover, as an ally; Harry is currently sleeping with Walter's wife, Dorothy (Rhonda Fleming), who he hopes can influence his boss; Griffith wants Ed Mobley (Dana Andrews), columnist and Pulitzer Prize winner, on his side, but Ed doesn't want to involve himself in the battle.
However, Ed's connections make him useful, and he decides to help Griffith. Ed's girlfriend, Nancy (Sally Forrest), is Loving's secretary and is willing to help to find the killer as well at the expense of her own safety, as part of a plan that Ed concocts with police lieutenant Burt Kaufman (Howard Duff).
While the City Sleeps demonstrates the following tropes:
- Answer Cut: As a very drunk Ed rides in a cab to Mildred's place, he murmurs "I wonder what the nice people are doing tonight." Cut to Nancy admiring the flowers Ed sent her.
- Ax-Crazy: The Lipstick Killer (played by John Barrymore Jr.).
- The Bait: Knowing that the Lipstick Killer will fall for the Batman Gambit, Ed uses Nancy as bait because making their engagement public will easily lure the killer after Ed made fun of him on national TV. Ed, of course, has arranged that a plainclothes policeman will follow Nancy everywhere she goes.
- Batman Gambit: How Ed concludes they will catch the killer. Set up an irresistible bait and wait for him to act like he normally would.
- Celebrity Paradox: Across the street from Nancy's apartment is a theatre showing a movie starring Dana Andrews.
- City Noir: The film takes place in New York (but it was actually shot in LA).
- Chalk Outline: Played Straight as we see one for the second murder.
- Cold Open: The film begins with the Lipstick Murderer’s first murder.
- Couldn't Find a Pen: The killer writes "Ask Mother" on the victim's wall in lipstick, hence the name.
- Digging Yourself Deeper: When Ed is trying to win back Nancy on the phone (and failing), he makes things worse when he starts to say "I don't want to be happy, I want...". She hangs up on him before he can finish.
- Extra! Extra! Read All About It!: How Griffith announces that he’s won the competition: he makes an extra edition announcing that he’s found the killer and the newspaper has the exclusive scoop.
- Film Noir: From the classic era, albeit a little grey-ish: it does have a lighter tone than must noirs.
- Freudian Excuse: The killer has serious mommy issues (because he was adopted) and was humiliated as a young kid (someone called him a girl).
- Friend on the Force: Lt. Kaufman, for Ed Mobley.
- Go Seduce My Archnemesis: Loving sics Mildred on Ed... which Mildred takes to mean that she is now a free agent, and promptly teams up with Griffith.
- Jerk with a Heart of Gold: It's shown in the very last scene that Walter Kyne took Ed's criticism to heart.
- Local Hangout: Dell’s: where everyone meets up after work and get very, very drunk (in the case of Ed and Mildred).
- The Profiler: Ed does a good job of figuring out the age, habits, and attitudes of the serial killer considering the limited evidence he leaves at the murder scene (he was, at least, a detective before becoming a writer). Ed then broadcasts his profile on his telecast to irritate the killer and make him do something stupid.
- Serial Killer: A serial killer is on the loose in New York City. Dubbed "The Lipstick Killer," he has also strangely become the center of a power struggle between three division chiefs in a media empire.
- Serial Killer Baiting: Mobley receives inside information about the Lipstick Killer from his police friend, Lt. Kaufman. After a new murder, the two men devise a plan to set a trap by using Mobley's fiancee Nancy as the bait, with Mobley taunting the Lipstick Killer on TV in order to bring him out into the open.
- Sexy Secretary: The curvaceous Nancy, Mark's secretary, who falls in love with Ed.
- Sexy Silhouette: The glorious Rhonda Fleming doing stretching exercises on the other side of a translucent screen. Subverted when the camera pans and reveals that Dorothy is actually wearing a bikini.
- Slasher Smile: The Lipstick Killer does this often.
- Upper-Class Twit: Walter is fairly clueless, but is cunning enough set his underlings up to vie with each other rather than try to upstage him.
- The Vamp: Mildred to Ed, much to Nancy’s chagrin; Dorothy Kyne as well.
- Villain Opening Scene: Opens with the Lipstick Killer murdering a woman in her apartment.
- "Where Are They Now?" Epilogue: Something of an accelerated case, as it takes place a bare several hours after the penultimate scene, with Nancy reading in a newspaper that various parties have been promoted or Put on a Bus.
- Wrongly Accused: The janitor found at the first murder is suspect number one for the police even if it’s only for very flimsy circumstantial evidence.