Sunday:

He wakes up, finding himself incarcerated in the alcohol detox ward of Bellevue Hospital [the actual hospital's alcoholic ward located in NYC] - a place termed "hangover plaza" by gay male nurse "Bim" (Frank Faylen). His blood had been analyzed and was found to be toxic: "straight Apple Jack, ninety-six proof." He is instructed on the ward's rules by the sadistic, taunting attendant who is experienced in dealing with alcoholics. Among other things, Birnam is told that Prohibition caused binge drinking and the rise of alcoholism:

The management insists. If we let you guys go home alone, a lot of you don't go home. You just hit the nearest bar and bounce right back again. What we call the quick ricochet...This department is sort of a half-way hospital, half-way jail...Listen, I can pick an alky with one eye shut. You're an alky. You'll come back. They all do. (gesturing toward other patients) Him, for instance. He shows up every month - just like the gas bill. And the one there with the glasses - another repeater. This is his forty-fifth trip. A big executive in the advertising business. A lovely fellow. Been coming here since 1927, good ol' Prohibition days. Say, you should have seen the joint then. This is nothing. Back then, we really had a turn-over. Standing-room only. Prohibition. That's what started most of these guys off - whoopee!

When Birnam refuses to swallow a mixture of paraldehyde to calm his stomach, the vindictive, spiteful Bim prepares him for the horrible, torturous, alcohol-induced nightmares of 'cold turkey' (the DT's - delirium tremens) he is doomed to experience later that evening:

They'll happen to be a little floor show later on around here. It might get on your nerves...Ever have the DT's?...You will, brother...After all, you're just a freshman. Wait'll you're a sophomore. That's when you start seeing the little animals. You know that stuff about pink elephants? That's the bunk. It's little animals! Little tiny turkeys in straw hats. Midget monkeys coming through the keyholes. See that guy over there? With him it's beetles. Come the night, he sees beetles crawling all over him. Has to be dark though. It's like the doctor was just telling me - delirium is a disease of the night. Good night.

In the middle of the night, in the drunk ward, Don wakens in sheer fright, helplessly exposed to fellow inmates screaming, shrieking, and suffering from delirium tremens. One patient is trussed-up with restraints after swatting at invisible beetles on his bed. The shadow from the chain-link pattern of the ward's door swings slowly over Don's bed. Taking advantage of the bedlam and confusion, he steals a doctor's overcoat, sneaks out, and escapes the imprisoning madness to make his way home in the pre-dawn hours.

Monday:

The milkman delivers another bottle of milk to Birnam's front door - making a total of four, where Helen sleeps and dutifully waits. Mrs. Deveridge (Mary Young), the busybody, long-suffering landlady from downstairs shreds any evidence of respectability that Helen might maintain about Don by telling her an abridged history of her drunken but "good-looking" five-year tenant:

I know what goes on in this house. I know Mr. Don Birnam. I knew all about him the first week they moved here five years ago. Heard those bottles rattle in the garbage can. I know all about you. You're Helen St. James, you're working on the Time Magazine, and you're his best girl. I also know he's not staying with any friends in Long Island. He's off on another toot and you know I'm darned right...I could have kicked him out fifty times - the last when two taxi drivers dumped him into the entrance hall out cold on the floor. With all my tenants going in and out and children leaving for school!...Well, I didn't put him out. Not as long as his brother could pay the rent. You couldn't help liking him anyway. He was so good-looking. He had such nice manners.

On his way home, a disheveled, stubble-bearded Don (wearing the doctor's overcoat and pajamas underneath) passes a liquor store and stares intently at the bottles - the camera shoots from inside the store through the front picture window. Looking pale and chalky white in the face, he lingers across the street in front of St. Agnes Church (on 43rd and Third Avenue) until the shopkeeper opens the store. He walks over and threateningly demands a quart of rye: "Come on, I need that liquor. I want it and I'm gonna get it. Do you understand? I'm gonna walk out of here with that quart of rye one way of another." He snatches the bottle without paying for it.

Before the film's most memorable, horrific scene [recalled in Roman Polanski's Repulsion (1965)], he has been consuming alcohol all day long. Alone in his apartment that evening, he experiences a demented, phantasmagoric, delirious hallucination. A small, squeaking rodent crawls out of a crack in one of the walls. And then, an artificial-looking, screeching bat flies and flaps about. He sinks back and cringes in his chair when it dives at him. It swoops down and kills the squealing mouse in front of his eyes - causing him to scream. As the creature is devoured, thick blood stains drip down the wall of the room. The screams alert the landlady, who calls Helen to come over and attend to him: "He's back. He's upstairs...I heard him yelling."

A faithful, still-loving and persistent Helen comes to his timely rescue. She finds him sprawled on the floor in front of his door, mumbling about his awful hallucination, how Bim had said "it's always little animals," and mentioning the warning that Nat had told him about the "ending" - he rhythmically clicks his fingers twice to signify his death: "Like this - or like that." He continues to repeat the gesture while the scene fades to black. [This is the point at which the pessimistic, down-beat film was originally to end.]

Tuesday:

The next morning, Don runs from the apartment with Helen's leopard coat - intending to pawn it so that he can provide for his next drink. Outside the pawn shop where she has followed, Helen demands the pawn ticket to redeem the sentimental coat - "the one that brought us together." When he refuses, she speaks to the pawnbroker herself, and learns that he swapped the coat for a gun ("something he hocked here a long while back") - for a suicide attempt.

In his apartment, he pens a suicide note to his brother: (The last page) "As for the services, dear old Wick, I'd recommend no flowers, and a few good jokes. Goodbye, Don." He loads the gun with bullets, and is ready to pull the trigger, but Helen returns and interrupts him - she sighs with relief to see him alive, but then notices the gun reflected in the mirror of his bathroom. Three options now become available to Birnam: (1) commit suicide by shooting himself, (2) get drunk once again (she begs him to drink: "Don't you want a drink, Don?"), or (3) become inspired to write:

Don: What are you up to?
Helen: Nothing. I'm just ashamed of the way I talk to you - like a narrow-minded, insensitive, small-town teetotaler.
Don: I told you, I don't feel like a drink. Not now.
Helen: Oh come on, Don, just one. I'll have one with you. I'm in no hurry. This is my easy day at the office.
Don: Look Helen, there are a few things I want to put in order before Wick comes.
Helen: Let me stay. Please!
Don: No! I don't want to sound rude, but I'm afraid you'll have to leave now.
Helen: Here, Don. (She hands him a drink glass.)
Don: You're very sweet. Goodbye...
Helen: You need this, Don. Drink it. I want you to drink it. I'll get you some more. I'll get you all you want.
Don: What kind of talk is that?
Helen: It's just that I'd rather have you drunk than dead.
Don: Who wants to be dead?
Helen: Stop lying to me.

He wrestles the gun from her and then tries to justify his suicide attempt - he is already psychically dead:

'Cause it's best all around for everybody. For you, for Wick, and for me...Look at it this way, Helen: this business is just a formality. Don Birnam is dead already. He died over this weekend...(He died) of a lot of things - of alcohol, of moral anemia, of fear, shame, DT's.

She begs him to save Don the writer by funneling his talent and ambition into his compositions:

Helen: There were two Dons. You told me so yourself. Don the Drunk and Don the Writer.
Don: Let's not go back to a fancy figure of speech. There's only one Don. He's through...I'm all right. I still have enough strength left.
Helen: I know you have. I can see it. Don't waste it by pulling a trigger, Don.
Don: Oh, let me get it over with. Or do you want me to give you another one of my promises that I never keep?
Helen: I don't want you to give me your promise. I don't want you to give your promise to anybody but Don Birnam.
Don: It's too late. I wouldn't know how to start.
Helen: The only way to start is to stop. There is no cure besides just stopping.
Don: Can't be done.
Helen: Other people have stopped.
Don: People with a purpose, with something to do.
Helen: You've got talent and ambition.
Don: Talent, ambition. That's dead long ago. That's drowned. That's drifting around in the bloated belly of a lake of alcohol.
Helen: No, it isn't. You still have it.
Don: Quit trying to stall me, Helen, it's too late. There's no more writing left in me. It's gone. What do you expect - a miracle?
Helen: Yes, yes, yes - if I could just make you...

The turning point for Don comes when the door buzzer rings - Nat has brought back his typewriter, left behind after his stairway accident: "I found this floating around on the Nile. She writes pretty good. I oiled her up a little. And I didn't oil her up so you can hock her." Helen interprets the return of his typewriter as a positive omen: "Someone somewhere sent it back - why? Because he means you to stay alive. Because he wants you to write. I didn't ask for a big miracle." The anxiety-prone writer is encouraged to resume The Bottle - the novel he started to write of his own experiences. He describes the familiar story of his own life and what he intended to write to exorcise his demons - now that he knows its more hopeful "ending":

Don: About a messed-up life, about a man and a woman and a bottle. About nightmares, horrors, humiliations, all the things I want to forget.
Helen: Put it all down on paper. Get rid of it that way. Tell it all to whom it may concern. And it concerns so many people, Don...Of course, you couldn't write the beginning 'cause you didn't know the ending. Only now - only now you know the ending.

Improbably, he is redeemed by the love of his forgiving, 'good' woman. With a determined commitment, he resolves to begin writing again, beginning with the events of the previous Thursday afternoon. Although he appears quickly rehabilitated, the outcome of his resoluteness is still vague and deliberately left ambiguous - he has yet to put down any lines for his first novel on paper.

In the film's final narration, he remembers how his 'drunkenness' was suspended out his window:

I'm gonna put this whole weekend down, minute by minute...The way I stood in there packing my suitcase, only my mind wasn't on the suitcase, and it wasn't on the weekend. Nor was it on the shirts I was putting in the suitcase either. My mind was hanging outside the window. It was suspended just about eighteen inches below. And out there in that great big concrete jungle, I wonder how many others that are like me. Poor bedeviled guys on fire with thirst. Such comical figures to the rest of the world as they stagger blindly towards another binge, another bender, another spree.

The film concludes with a backward-moving zoom-out shot from his window as he packs his suitcase. The camera retreats from the window, and then pans left across the building and cityscape - reversing the action that occurred in the opening minute of the film.