Macabéa has just moved to the big city after her aunt, who raised her, died. She gets a job as a typist and moves into a boarding house with three other women. In her spare time, she listens to a radio station called Time; on Sundays, she likes to ride the metro. Then she meets Olímpico, a northeasterner like herself, who has dreams of becoming a congressman.
On Jo's birthday, her mother, and later, her father, discover that she is not a virgin anymore - she is taking pills. The birthday party turns into a complete mess, since Jo's mother can not hold herself and accuses her daughter in front of all guests of not being a child that everyone thought she still was. Jo rebels and leaves the house, and discovers that her boyfriend listened to everything and did not help her. She decides to leave him, and to start her life again. As a woman, now.