Lucía Escobar, best known as Lucy, is a young and poor girl who lives in the countryside of Buenos Aires. Although she is inferior to rich people, she is happy because she has her parents, and because she teaches little poor children of the small town where she lives. Lucy has to face discrimination many times, being called a "Cabecita" by rich people. Even though, she is happy. But everything changes when her father is killed. Lucy knows that the answer to the death of her father has something to do with her mother`s mysterious past (she was a rich girl who left her family to live with a poor man), and the only way to find out who killed her father and take revenge is to travel to Buenos Aires, the capital city, and investigate. From then on, Lucy`s life will not be the same again.