u/Successful_Length109

It’s been bugging me for decades

It’s black and white film, probably from the 30’s-50’s and this happens at the end; a man fools a woman into revealing that she is a killer. He gives her truth serum type medicine (or pills??) which makes her sleepy then moves a clock’s hands forward to make her think the time is later than it is. She thinks that an ex lover (who has been found wrongly guilty and is due to be hanged) is now dead but really he is still going to be alive for a short time. After she makes her drugged confession this one man from earlier calls the police to report it and save her ex’s life.

Any clues?? A Million thanks.