The Big Clock (1948)

In director John Farrow's film noirish suspenseful thriller (later updated as the spy thriller No Way Out (1987) with Kevin Costner):

• the opening scene of 1940's New York media executive and Crimeways weekly magazine journalist George Stroud (Ray Milland) inside his company's gigantic $600,000 privately-owned corporate clock in the building's lobby (which synchronized with all other clocks in the entire building and in secondary printing plants and dozens of other foreign bureaus) - in a symbolic race against time to clear his own name (as he narrated what had happened to him: "How'd I get into this rat race anyway? I'm no criminal. What happened? When did it all start? Just 36 hours ago, I was down there crossing that lobby on my way to work, minding my own business, looking forward to my first vacation in years. 36 hours ago, I was a decent, respectable, law-abiding citizen with a wife and a kid and a big job. Just 36 hours ago by the big clock")
• the flashback to 36 hours earlier when Stroud was implicated in the murder of his clock-obsessed, ruthless and detestable boss Earl Janoth's (Charles Laughton) blonde mistress Pauline York (Rita Johnson); Janoth was the possibly homosexual, powerful publishing tycoon of NYC's Crimeways Magazine
• before entering Pauline's apartment, Janoth noticed someone else who had just left Pauline's apartment just as he arrived, but did not see the man's face; before killing Pauline, Janoth had pressured her to identify her other lover - and she elusively claimed that his name was "Jefferson Randolph" to protect Stroud; to cover up his crime, Janoth cleverly planned to blame the murder on this other man

Janoth's Murder of His Mistress Pauline (She Claimed Her Other Lover was "Jefferson Randolph" To Protect Stroud)

• the intense scene of the jealous Janoth killing Pauline after accusing her of having another lover - she snapped back that he was a "cheap imitation Napoleon" and called him "disgusting...flabby"; he struck her in the head with a phallic-shaped, heavy metal sundial - and there was a contorted closeup of Janoth's grotesque face with a twitching upper lip
• the ensuing cat-and-mouse game by Stroud who was enlisted by Janoth to find the killer (who was witnessed accompanying Pauline during the evening by many individuals); Stroud feared that his investigation would lead to only one man - himself!; he realized that all the clues pointed to himself as the prime suspect, so he attempted to steer the manhunt away from himself, and find information to incriminate Janoth by using a method of "irrelevant clues"
• the taut confrontational scene at the film's end when the framed Stroud , accused Janoth's right-hand man Steve Hagen (George Macready) of being the killer in order to smoke out Janoth - causing a raging Janoth to shoot Hagen (after he confessed: "Janoth killed Pauline") and then Janoth's fall to his death down the building's elevator shaft in his attempted escape