Gustav von Aschenbach is an aging German writer who is the paragon of solemn dignity and fastidious self-discipline. Determinedly cerebral and duty-bound, he believes that true art is produced only in "defiant despite" of corrupting passions and physical weaknesses.

When Aschenbach has the urge to travel, he tells himself that he might find artistic inspiration from a change of scene. Aschenbach's subsequent trip to Venice is the first indulgence he has allowed himself in years; it signals the beginning of his decline. Aschenbach allows the languid Venetian atmosphere and gently rocking gondolas to lull him into a defenseless state. At his hotel he notices an extremely beautiful fourteen-year-old Polish boy named Tadzio, who is visiting with his mother, sisters, and governess. At first, Aschenbach's interest in the boy is purely aesthetic, or so he tells himself. However, he soon falls deeply and obsessively in love with the boy, although the two never have direct contact.

Aschenbach spends days on end watching Tadzio play on the beach, even following his family around the streets of Venice. Cholera infects the city, and although the authorities try to conceal the danger from the tourists, Aschenbach soon learns the facts about the lethal epidemic. However, he cannot bear to leave Tadzio and stays on in Venice. He becomes progressively daring in his pursuit of the boy, gradually becoming more and more debased, until he finally dies of the cholera, degraded, a slave to his passions, stripped of his dignity.