Dudley Moore plays New Yorker Arthur Bach, rich, alcoholic and incredibly spoiled. Heir to a chunk of his family’s vast fortune, he is told he will only inherit if he marries Susan Johnson (Jill Eikenberry), the daughter of a business acquaintance of his father.
Herein lies Arthur’s problem; he does not and intends never to love Susan. Unfortunately, his family have different feelings on the subject. Fed up by his drunken antics, they think she will inject some much-needed maturity into Arthur.
On a trip into Manhattan, Arthur and his valet Hobson (John Gielgud in an Oscar-winning performance) witness a young woman, Linda Morolla (Liza Minnelli), doing a bit of shoplifting. After intervening with the security guard, Arthur asks her for a date. How will the family feel about this latest dalliance?
Arthur shares his feelings for Linda with his grandmother Martha (Geraldine Fitzgerald), but to no avail. Hobson, in a more-like-a-father-than-his real-father moment, encourages Linda to attend Arthur’s engagement party. Hobson, you see, believes that Arthur is beginning to grow up and it’s down to her.
So, Linda crashes the engagement party and in a yeah-right moment, she and Arthur spend time alone together – a fact noticed by both families.
An old man, Hobson is later hospitalised. Arthur rushes to his side and vows to care for the person who has long cared for him. Several weeks later, Hobson dies and the previously sober Arthur goes on a drinking binge. On the day of his supposed wedding to Susan, Arthur visits Linda at the diner where she works and proposes to her.
He then tells Susan that there will be no marriage. Her enraged father, Burt begins to attack Arthur, landing several meaty blows. Linda arrives and tries to intercede. At this point, Burt grabs a cheese knife and goes after the pair. They are saved by the intervention of Grandmother Martha, who slaps Burt, bringing him out of his murderous haze.
A wounded and groggy Arthur announces to the congregation that there will be no wedding then passes out. Later Linda attends to his wounds and they discuss living and him having to get a job. A horrified Martha overhears and tells Arthur that he can have his fortune because no Bach has ever been working class. The happy couple is driven off through Central Park by Arthur’s chauffeur Bitterman.