It Happened One Night (1934) is one of the greatest romantic comedies in film history, and a film that has endured in popularity. It is considered one of the pioneering "screwball" romantic comedies of its time, setting the pattern for many years afterwards along with another contemporary film, The Thin Man (1934).

The escapist theme of the film, appropriate during the Depression Era, is the story of the unlikely romantic pairing of a mis-matched couple - a gruff and indifferent, recently-fired newspaper man (Gable) and a snobbish, superior-acting heiress (Colbert) - a runaway on the lam. It is a reversal of the Cinderella story (the heroine rejects her wealthy lifestyle), a modern tale with light-hearted sex appeal in which courtship and love triumph over class conflicts, socio-economic differences, and verbal battles of wit.

The madcap film from Columbia Studios (one of the lesser studios) was an unexpected runaway box office sleeper hit (especially after it began to play in small-town theaters), and it garnered the top five Academy Awards (unrivaled until 1975, forty-one years later by One Flew Over the Cuckoo's Nest (1975) - and then again by The Silence of the Lambs (1991).) It won all five of its nominated categories: Best Picture, Best Actor (Clark Gable), Best Actress (Claudette Colbert), Best Director (Frank Capra), and Best Adaptation (Robert Riskin).

The film, composed mostly of a road trip (by bus, car, foot, and by thumb in locales such as bus depots or interiors of buses, and the open road) by the social-class-unmatched couple, contains some of the most classic scenes ever made: the "Walls of Jericho" scene in an auto-camp bungalow so that they can sleep in the same room out of wedlock, the doughnuts-dunking lesson, the hitchhiking scene, the night-time scene on a haystack in a deserted barn, and the dramatic wedding scene. With his good-natured, street-smart, and breezy performance, Gable influenced the un-sale of undershirts by taking off his shirt and exposing his bare chest, and bus travel by women substantially increased as a result of the film.

Capra had originally wanted MGM stars Robert Montgomery and Myrna Loy to play the lead roles, but ended up, surprisingly, with top MGM star Gable 'on-loan' (as punishment for refusing a role opposite Joan Crawford) from the studio. [Another Montgomery film, Fugitive Lovers (1934) with a semi-similar tale was released at the same time by MGM.] Others who turned down the female lead role, before Colbert accepted the four weeks of work for $50,000, included Miriam Hopkins, Margaret Sullavan, and Constance Bennett.

The screenplay, co-written by director Frank Capra (uncredited) and Robert Riskin, was based on an August 1933 Cosmopolitan magazine story titled "Night Bus" by Samuel Hopkins Adams. [Another of Adams' short stories about a woman traveling on a bus, "Last Trip" in the March edition of Collier's Magazine, may also be considered a source for the film.] In both 1945 and 1956, it was remade as musicals: Eve Knew Her Apples (1945) starring Ann Miller, and You Can't Run Away From It (1956) with Jack Lemmon and June Allyson.

Animation expert Friz Freleng, in his unpublished memoirs, claimed that the film helped to inspire the creation of various cartoon characters:

• Bugs Bunny's fast-talking personality was partially based on Oscar Shapeley (Roscoe Karns), and also related to the one mention by Gable of an imaginary hitman named 'Bugs' in the film; (Bugs Bunny's debut film was Porky's Hare Hunt (1938)); Bugs Bunny's carrot-eating technique was based on Peter Warne (Clark Gable) and the way he talked while chewing on a carrot
• Yosemite Sam was inspired by Alexander Andrews (Walter Connolly)
• Pepe LePew was inspired by King Westley (Jameson Thomas)

The film's opening line is the question that the portly, millionaire tycoon father Alexander Andrews (Walter Connolly) asks about his angry daughter's behavior and refusal to eat:

Hunger strike, eh? How long has this been going on?

On his yacht moored in the sunny waters off Florida with him is his spoiled, stubborn, devil-may-care headstrong heiress daughter Ellie Andrews (Claudette Colbert). In an impulsive moment and possibly to spite her father, she has just married (in name only) a worthless playboy, King Westley (Jameson Thomas), a fortune-hunting, ne'er-do-well celebrity aviator. Objecting to the wedding, although Westley is in her own upper social class, Mr. Andrews has kidnapped his daughter and brought her aboard his yacht, holding her as a prisoner against her will. He plans to annul the unconsummated marriage to the mercenary, worthless, stuffed-shirt playboy he despises.

Ellie is first seen backed up against a stateroom wall by her father - both are engaged in a vicious argument. In a temper tantrum, Ellie defiantly shouts at her father for controlling her life ("I'm over twenty-one and so is he") and not letting her assert her freedom:

Ellie You've been telling me what not to do ever since I can remember.
Mr. Andrews: That's because you've always been a stubborn idiot.
Ellie: I come from a long line of stubborn idiots.

She knocks away her father's fork (with a piece of steak on it), overturns his tray of food all over the floor, and he reacts by slapping her - she is surprised. Fully clothed, she rushes up on deck, up onto the railing and effortlessly dives overboard, and then swims ashore to freedom and independence - as if it were that simple to 'jump ship'. Her father helplessly watches as she swims away, and calls for his staff to "lower the boats." Detectives are dispatched to find her - "Watch all roads, airports and railway stations in Miami."

The next scene is introduced by a sign reading: Night Bus to New York. In the Miami bus station, detectives can't believe she would take a lower-class night bus. "We're wasting our time. Can you imagine Ellie Andrews riding on a bus?" To evade her father's search by traveling incognito, she has another elderly lady buy a ticket for her on a Greyhound bus - a rickety, proletarian means of transportation which would be unlikely for a rich heiress. She is determined to escape detection and join her husband (to spite her father) after a night bus ride from Miami, Florida to New York.

The other major character in the film is tall, outspoken newspaper reporter Peter Warne (Clark Gable), who is first seen surrounded by a mob of onlookers listening to "history in the making" as he is arguing with his fatherly editor-boss Joe Gordon (Charles C. Wilson) in a telephone booth in another part of the bus station. He has recently been fired for drinking on the job - and turning in a story in "free verse." He drunkenly tells off his boss on the other end of the line:

In a pig's eye, you will!...Hey listen monkey face, when you fired me, you fired the best newshound your filthy scandal sheet ever had...That was free verse, you gashouse palooka!

The crowd outside the phone booth has overheard his side of the conversation and believes he has won the argument, but he has been play-acting - his boss is no longer on the line. With a headstrong display of an assertive will and dramatic theatricality, he shouts into the receiver and declares his independence from the newspaper (as Ellie did against familial control) long after he has been fired and disconnected: "Oh, so you're changing your tune, eh? You're a little late with your apologies. I wouldn't go back to work for you if you begged me on your hands and knees. And I hope this will be a lesson to you!" [Onlookers refer to Peter Warne as "the King" -- Gable's nickname in real life.]

Peter, like another 'father-less' passenger, has also purchased a ticket for the crowded night bus ride to New York, traveling on the bus because he is down-and-out and broke, and that is the only fare he can afford. These circumstances will soon bring the two main characters together and contrast their status in the social hierarchy. The only bus seat left is in the back of the bus, and it is covered with a bundle of newspapers - Warne hurls through the window to the platform. After the bus driver (Ward Bond) objects to his brash action, he replies:

I never did like the idea of sitting on newspaper. I did it once, and all the headlines came off on my white pants. On the level! It actually happened. Nobody bought a paper that day. They just followed me around over town and read the news on the seat of my pants.

While he is engaged in an altercation with the driver, Ellie quickly takes the seat that he has cleared off. In their first encounter together, he orders her out of his seat: "Now listen, I put up a stiff fight for that seat. So if it's just the same to you - scram." But since it is the last seat on the bus, and the seats are "first come, first serve," they must share it. The front of the bus fills the screen, with its several state licenses, lit headlights, and its destination over the front window: NEW YORK. As the bus lurches forward while she is obstinately putting her own bag up in the rack, she is thrown into his lap. He tells her: "Next time you drop in, bring your folks."

At a night-time rest stop, where 5 cent cones and hot dogs and hamburgers for 10 cents are advertised, Ellie listlessly leans up against the side of the bus, smoking a cigarette. Her small briefcase is stolen with all her money in it (except four dollars). Peter acts gentlemanly, but is unable to catch and apprehend the thief for her. To his surprise, she refuses to have it reported, so that she won't be found out: "I don't want it reported!...Can you understand English? Would you please keep out of my affairs. I want to be left alone." He recognizes that she is a spoiled brat: "Why, you ungrateful brat!"

At the next stop, a thirty-minute breakfast stop in Jacksonville, Ellie has finally fallen asleep next to the newspaperman. She wakes up clutching his lapel, with her head nestled on his shoulder. She asks the driver to wait for her, expecting the bus to wait while she has a leisurely breakfast. The bus takes off without her when she returns twenty minutes late. Peter deliberately misses the bus too, reacquainting himself:

Remember me? I'm the fellow you slept on last night.

The next bus leaves twelve hours later, but she reminds him of her independence: "You needn't concern yourself about me. I can take care of myself."

Then he reveals to her that he knows her true identity: "You'll never get away with it, Miss Andrews." During the stop, he had discovered who she is - a runaway heiress - through a front-page headline in the Florida Journal newspaper - ELLEN ANDREWS ESCAPES FATHER. Acting in character, knowing that money can get her anything she wants, Ellie bribes him into not informing her father about her whereabouts - while touching his chest: "Listen, if you promise not to do it, I'll pay you. I'll pay you as much as he will. You won't gain anything by giving me away, as long I'm willing to make it worth your while. I've got to get to New York without being stopped. It's terribly important to me." Again, Peter berates her as a spoiled brat:

You know, I had you pegged right from the jump. Just a spoiled brat of a rich father. The only way you get anything is to buy it, isn't it? You're in a jam and all you can think of is your money. It never failed, did it? Ever hear of the word humility? No, you wouldn't. I guess it would never occur to you to just say, 'Please mister, I'm in trouble, will you help me?' No, that would bring you down off your high horse for a minute. Well, let me tell you something, maybe it will take a load off your mind. You don't have to worry about me. I'm not interested in your money or your problem. You, King Westley, your father. You're all a lot of hooey to me!

At the Western Union office, he telegrams his New York Mail boss, Joe Gordon, about a possible scoop - sending it collect:

Am I laughing? The biggest scoop of the year just dropped in my lap. I know where Ellen Andrews is...How would you like to have the story, you big tub of mush...Will try and get it. What I said about never writing another line for you still goes. Are you burning? PETER WARNE