The Lost Weekend (1945 Billy Wilder)

Powerful, brilliantly written (by Wilder and Charles Brackett) look at failing alcoholic writer (source novel by Charles R Jackson, himself an alcoholic and addict).

Ray Milland great as drunk, Jane Wyman his girl, Howard da Silva makes an impression as the barman, Phillip Terry is the brother, and Frank Faylen a slightly sinister nurse.

Examples of great writing:

"One's too many and a hundred's not enough."
"We have quite a supply of milk."
All the pawnbrokers are shut because it's Yom Kippur - even the Irish ones (so they in turn can all be closed on St Patrick's Day also).
Doris Dowling (Gloria): "I waited half the night like it was the first date I ever had."

And directing:

The bathroom mirror.
The bottle hanging out of the window.
The bottle that's in the ceiling lamp.

And lighting:

Rain patterns over walls in end sequence (John Seitz).

Oscar wins (film, actor, director, screenplay) and nominations (Doane Harrison, Seitz, Rózsa). Best film at Cannes.