Billy Wilder - The Lost Weekend (1945)

Don Birnam is an alcoholic. His brother Wick and girlfriend Helen know but believe that he is on the wagon, a belief he does his best not to shatter. They try to keep him sober and healthy by arranging trips and other such events. One is this weekend - Don and Wick are heading to the country. However, Don manages to delay the trip and then evade it altogether, in order to get drunk in a bar. He has no money, so often ends up getting his alcohol by more and more outlandish and nefarious means. He does have two things going for him: Helen loves him and will do anything to see him shake his addiction. The other is that he has a great talent for writing, and has great ambition in that regard. However, his productivity as a writer is undermined by his alcoholism, creating a downward spiral of despair and addiction. Sensing his own plight, his thoughts turn darker.