Jim Dixon, a junior lecturer in history at a provincial English university in the years after World War II, nears the end of his first year at the school. Dixon has not made a good impression upon the faculty and knows that his superior, the absent-minded Professor Welch, could ask him to leave at the end of term next month. Fearful of making further bad impressions or revealing his inner disgust for Welch, Dixon agrees to give the end-of-term lecture on the theme of "Merrie England" and to stay with the Welches the following weekend for a weekend of music and the arts.
At the party, Dixon meets Welch's son Bertrand and his girlfriend Christine, who have come up to the country from London. Bertrand, an artist, seems pretentious, while Christine seems uptight and unattainable. Dixon escapes to the pub and returns to the Welches' later that night, where he makes a drunken pass at Margaret Peel, a friend and colleague. Margaret has been staying with the Welches as she recovers from a recent suicide attempt caused by a recent break-up. Dixon and Margaret's friendship has rapidly been moving toward something more intimate, thanks to Margaret's subtle pressure and Dixon's pity and good-natured concern for Margaret.
Margaret kicks Dixon out of her room, and he falls asleep while smoking a cigarette. Dixon wakes up in the morning to find he has burned holes in his bedsheets. Afraid of further damaging his chances of keeping his job, Dixon attempts to hide the damage. Christine unexpectedly find Dixon's dilemma funny and agrees to help him.
Dixon thinks about Christine but does not see her again until the college's Summer Ball a couple of weeks later. Margaret and Bertrand both spend the night hanging around Christine's rich uncle Gore-Urquhart, who Bertrand hopes to work for. Dixon's friend Carol Goldsmith finally convinces Dixon to make a move for Christine by revealing that she has been having an affair with Bertrand. Dixon rallies his courage and asks Christine, whom Bertrand has been ignoring, to let him take her home early. Christine agrees and explains to Dixon in the taxi how Bertrand has been mistreating her. Back at the Welches', Christine and Dixon kiss and agree to see each other in two days. When they meet again, however, they decide not to see anymore of each other because of their respective obligations to both Bertrand and Margaret.
Dixon spends the following week planning to write his "Merrie England" lecture in a nostalgic way that will appeal to Professor Welch, but Welch himself keeps Dixon preoccupied with menial fact-checking for Welch's own work. On the day of Dixon's lecture, Bertrand comes to Dixon's room and accuses Dixon of seeing Christine behind his back. Bertrand tells Dixon that Dixon is wasting his time and Dixon, fed up with Bertrand's hypocrisy and condescending bossiness, gets in a fight with Bertrand. Bertrand gives Dixon a black eye and Dixon knocks him down.
Shaken up and nervous, Dixon drinks quite a lot at the reception before his lecture. He is drunk when he gives the lecture, and inadvertently imitates the voices of Professor Welch and the college Principal in the opening segments. Dixon rounds out the lecture by expressing his contempt for the subject before he passes out. The next day, Dixon finds he has been fired, but is offered a well-paying job in London by Gore-Urquhart.
The same day, Dixon meets with Catchpole, the man who supposedly inspired Margaret's suicide attempt. Catchpole reveals that Margaret faked the suicide attempt in order to gain sympathy from Dixon and Catchpole. Dixon arrives home from this meeting to receive a message from Christine, asking him to meet her at the train station before her she returns to London. Dixon arrives at the station late, but so does Christine. Christine tells Dixon that she knows of Bertrand's affair with Carol and has broken off their relationship. Dixon tells Christine that he is through with Margaret. Dixon reveals the news about the job offer from Christine's uncle, Gore-Urquhart, and asks to return to London with Christine. As they walk down the street, they run into the Welch family, whom Dixon salutes with an explosive laugh of contempt.