Segovia, 1559. Lucía de Avellaneda celebrates her engagement party with the Marquis of Peñarrosa, a nobleman chosen by her brother. This marriage promises to reinforce the financial and social status of the family, but, in the middle of the celebration, the fiancée receives an unexpected letter from a woman who claims to be her mother and who claims her on her deathbed. Lucía shows up at the beguinage, where her mother has summoned her. In this place she lives with other women independently and outside the Church. The young woman opens up to a new world that will make her question everything she had known until now. And she, furthermore, will know love through a pure and uncontrollable, but forbidden, passion.