“- Helen St. James: There must be a reason why you drink, Don? The right doctor could find it.
– Don Birnam: Look, I’m way ahead of the right doctor. I know the reason. The reason is me – what I am. Or, rather, what I’m not. What I wanted to become and didn’t.”

You’d be forgiven then for thinking the 1946 best picture winner, a drama about alcoholism, would be another classroom-ready tale of melodramatic moralizing. But Billy Wilder’s devastating drama The Lost Weekend is a film of greater complexity than we’re used to seeing at the Oscars and remains one of the most uncompromising and important films about an illness that at the time wasn’t fully understood.

Based on Charles R Jackson’s 1944 novel, it focuses on Don (Ray Milland) who sees himself as a writer but, well, doesn’t really do much writing. Instead, he drinks. A lot. It’s a concern of both his brother Wick (Philip Terry) and his girlfriend Helen (Jane Wyman) who struggle to deal with him, growing increasingly exasperated with his irrational behavior. The film takes place over a disastrous weekend, one that was supposed to see the two brothers head out of the city, away from temptation. But a last-minute change of plan, deviously engineered by Don, sees him free from their joint glare and heading to the bar …

For an addiction that affects around one in 12 people, there’s a remarkable lack of genuinely well-constructed films about the effects of alcoholism and Wilder’s intent initially wasn’t one of nobility. His interest in shining a light on a disease that many fail to understand was reportedly a secondary motivation. He’d just worked with Raymond Chandler on the screenplay for Double Indemnity and seen firsthand recovering alcoholic Chandler turn back to the bottle after a tumultuous writing process. Making this film was his way of trying to understand Chandler better and it’s this arguably simplistic reason that ironically leads to a more developed character study.

This is a film noir without any crime or evildoing. The darkness on screen comes from an untreated addiction and how such toxicity threatens to ruin a man’s life. Wilder, who also co-wrote the script with Charles Brackett, avoids inserting a host of unnecessary dramatic conflicts into the story and focuses on the grimy day-to-day minutiae of being an alcoholic. Don’s primary focus is to drink and every scene is haunted by this destructive, debilitating need. You can see it in Milland’s wonderful Oscar-winning performance, driven by this animalistic urge, veering from manic to crestfallen with a sip of rye. Drunk acting isn’t easy, as many wildly overexaggerated performances have since shown us, but there’s an uncomfortable authenticity to Milland’s take on Don. Together with an Oscar-winning screenplay, an indelible image is created and I’ve been haunted by it ever since.

Addiction is crippling for the addict but it’s also heartbreaking for those close enough to smell the booze. Don’s brother and girlfriend are both understandably exhausted with him but, given the time period, they’re also a tad dismissive. Don isn’t an alcoholic but just someone who “drinks a few too many”, a damning description that means that no one in his life is taking the condition with the gravity it requires. But we’re also shown the other extreme when Don wakes up to find himself at “Hangover Plaza” – a ward for alcoholics, a screaming horror show of men being misunderstood by uncaring orderlies. There’s nowhere for Don to turn, nowhere for him to truly get help and the grubby impossibility of his situation becomes suffocating.

It also leads Wilder down a rather difficult path and it’s in the final stretch that the film slips up. The original ending of the novel grimly suggested that Don was beyond help and his addiction would most likely be the end of him. On screen, the spiral into oblivion is abruptly rerouted and we’re offered a seemingly pat conclusion that solves Don’s alcoholism with alarming, and annoying, ease as he combines the love of his girlfriend with the drive to write. Wilder denied that it was as happy as it might seem, however. “We don’t say that the man is cured,” he said. “We just try to suggest that if he can lick his illness long enough to put some words down on paper, then there must be some hope.”

Happy/ambiguous/frustrating finale aside, it’s an undeniably brave and startling piece of work although it wasn’t always seen as such. Initial test audiences laughed at Don’s drunken behavior while Paramount execs were tempted to shelve the film after a $5m offer from the liquor industry to bury it. But 75 years later, its portrayal of the self-deceptive danger of alcoholism is strangely unsurpassed.