While attending law school, honor student David Maldon is awarded a job at the prestigious law firm of Belney, Parkford, Evans and Hughes. One day, at a birthday cocktail party for the law firm's senior partner, John Belney, David behaves in an erratic manner after consuming just one drink. His behavior catches the notice of John's daughter Mary, an attractive psychoanalyst, who accuses John of being drunk. In private, John denies the accusation and explains that he suffers from "liquor recoil," a condition he developed during World War II, when he nearly drowned in a vat of brandy at a French monastery. Realizing that David gets drunk at the mere mention of alcohol, Mary saves him from further humiliation by sending him home.
In the hope of curing himself of his sensitivity to alcohol, David decides to take a teaspoonful of brandy every night before going to bed. The experiment appears doomed to failure, however, when David begins imagining that his dog is talking to him.
The day after John's birthday party, Mary, who has fallen in love with David, offers to help David overcome his problem. Intrigued by David's claim that his dog talks to him, Mary offers him a glass of brandy and observes him conversing with his dog.
One day, at the law office, David is present when Carl Bellcap, the city attorney, threatens to sue John if he allows one of his clients, the manager of a luxury apartment building, to evict the Lees, a Chinese couple. Carl also warns John that if the pregnant wife of the Chinese doctor loses her child, he will charge the law firm with causing her undue trauma and will hold it responsible. When Dr. Lee's wife loses her child in childbirth, David, working without the consent of the attorneys at his firm, contacts the management company and insists that the Lees be returned to their apartment.
Later, at an alumni dinner, Charles Parkford, the partner at the law firm who is responsible for the eviction of the Chinese couple, learns that David is allergic to alcohol and decides to take revenge on his initiative by secretly slipping some wine into his soup. The wine makes David instantly drunk, and he embarrasses himself by singing with the band.
When David regains his sobriety, he accuses Bellcap of compromising his responsibilities as a public servant to gain favor with the partners at the law firm. Bellcap admits that he is seeking a job at the law firm, but tells David that he has been stymied in his efforts to fight rich and powerful law firms like John's because few talented lawyers are willing to work for the city. Convinced that Bellcap has done the best he could to fight the many injustices in the city, David apologizes to him.
In the final scene, at his law school graduation ceremony, David announces his resignation from John's law firm, and accepts a job with the city attorney's office. Though Mary prefers that David remain with her father's firm, she respects his principles and plans to marry him.