Maria, a young nun, spends more time outdoors than indoors, much to the disdain of her fellow nuns. Thus, Mother Abbess sends Maria to become a temporary governess to the seven children of Captain von Trapp, a widower and retired navy officer.

Maria, although initially hesitant, arrives at the von Trapp house, and gets to know the Captain and the children. At dinner, Captain von Trapp announces that he will be going to Vienna.

While the Captain is in Vienna, Maria takes the children on outings, and teaches them to sing. Slowly, she wins both their love and respect. Soon, however, the Captain returns with his friends from Vienna, the Baroness and Max. He discovers, to his horror, that his children have been out of the house playing, and harshly reprimands Maria. However, he is moved by the sound of the music that Maria taught the children to sing. Deeply moved, he thanks Maria for bringing music back into his house, and urges her to stay.

Captain von Trapp throws a party in honour of the Baroness. There, the Baroness senses Maria's love for the Captain. Feeling threatened, she successfully persuades Maria into returning to the abbey.

In the abbey, Maria learns from Mother Superior to face up to her problems instead of running away from them. She returns to the von Trapp house only to discover that the Captain has decided to marry the Baroness. Still, the Captain cannot hide his true feelings for Maria. The Baroness, now painfully aware, gracefully bows out. Maria and the Captain fall in love, and they get married.

Not long after, Hitler occupies Austria. The Captain is summoned to return to the Navy, but refuses to. Instead, the family escape from the soldiers trying to capture the Captain, and escape into Switzerland, climbing every mountain.