Given the question: Build a movie plot around this: Who knocked someone unconscious? the killer
The answer is:
In Sydney in 1952 and returning from a month away, the private investigator Reilly finds his office has been taken over by the building's janitor, Jerry Vane, who has been impersonating him in his absence. Roughing Vane over, Reilly discovers he has taken a missing person's case in which an insurance company is trying to locate someone named Alex Pleshette. However, when Reilly presents himself to the insurance office to drop the case, the owner Max Arnett claims he never hired his agency to begin with. On the way out however, Arnett's receptionist inadvertently gives away the truth that Reilly was in fact hired.Heading back to his office, Reilly is confronted by two thugs in an alley who beat him and tell him to lay off the Pleshette case. In his office a short time later, a beautiful young woman in black arrives. Presenting herself as Mrs. Pleshette, Reilly assumes she is Alex Pleshette's wife, however she curtly informs him that her husband is dead, and that she is actually Alexandra, better known as Alex Pleshette. She tells him to stop interfering as she is now no longer missing, and departs leaving him even more confused.Next day, Reilly finds out from his police detective friend Jack Bosley that Alex Pleshette witnessed the murder of her husband, a wealthy tycoon named Donald Pleshette who was at the time being investigated for company insurance fraud. However, she was knocked unconscious by the killer and as a result is unable to remember the event. Not long after this, she went missing and no one knew where she was, not even her lover Gabe Preston, her husband's disgruntled business partner. Reilly recognizes that Preston would thus have a motive for murder, but Bosley explains that he has a strong alibi.Later, Reilly gives Vane a camera and instructs him to follow Arnett and take photos of anything that appears interesting. Meanwhile, he drives to the Pleshette mansion on Noir Drive to confront Alex. She concedes that although she was bitter towards her husband as a result of the fraud...