Teenage Odilia, the book’s narrator, describes the summer of the mariposas, or butterflies. Almost a year after her father leaves, the drought ends in Texas. She recalls the butterflies landing on everything. That summer, her mother stops being a housewife, admits that her husband has left, and gets a job at a diner to support her five daughters. She instructs the sisters to stay indoors and play Lotería. However, since they are unsupervised, the girls neglect their chores and do as they please. Odilia recalls, “[We] finally had the freedom to do whatever we wanted, wherever we wanted, whenever we wanted” (3). Some days they hike the hills beyond El Indio Highway, following the butterflies. They rest and swim by the Rio Grande. On one such day, they find a dead body in the river.

Chapter 1 introduces the Garza sisters: Odilia, the responsible eldest sister; Juanita, the headstrong 14-year-old who fancies herself smarter than the group; beautiful but vain twins Velia and Delia; and youngest sister Pita. The siblings debate over what to do with the body. While Odilia mulls over whether to alert the authorities, Juanita finds a wad of cash and a Mexican driver’s license in the dead man’s pocket.