Adela “Addie” Ramírez is a 12-year-old Mexican American girl and the protagonist of the book. The story is told through her perspective. She lives with her mother, Lourdes, and stepfather, Alex, in Thorne, New Mexico. At the start of the book, she does not know her biological father, as Lourdes refuses to talk about him. Lourdes’s pregnancy and Alex’s proposition that he officially adopt Addie intensifies her curiosity about her biological father and sets in motion the events in the book.

Addie is intelligent and curious; she is interested in and fascinated by science and history, and contextualizes her learning in school with respect to her own life. For instance, she thinks about what she has learned about genes when she wonders how much of who she is has been inherited from her father. She also researches the Bravo family when she learns that they are related to her. These traits, combined with an inherent tenacity, enable Addie to find clues about her biological father and decipher his identity.

Addie is also an honest and sincere young girl with a strong sense of right and wrong. Her desire to learn more about her family motivates her to take the Bravo biography home from the historical society, but she returns it and owns up to her mistake soon after.