In 1825 when Josefina trusts a trader in Santa Fe with an important deal, she makes a surprising discovery about this young American who leaves town without paying her.
Josefina and her sisters distrust learning to read and write, as well as other changes their Tía Dolores is bringing to the household, because they fear they will lose their memories of their mother.
When a dashing man from Mexico City brings Tia Dolores a ruby ring for Christmas, Josefina notices that things start going wrong and she decides to get to the bottom of the mystery.
When Tia Dolores, the beloved aunt who has cared for the Montoya family since the death of their mother, announces that she is planning to leave, Josefina and her sisters try to find a way to change her mind.
Josefina hopes to become a "curandera" or healer like Tia Magdalena, and she is tested just before her tenth birthday when a friend receives a potentially fatal snakebite.
The second Christmas after their mother has died, Josefina and her three sisters find that participating in the traditions of Las Posadas helps keep memories of Mamá alive.