In a convent of cloistered nuns at the end of 19th century, the community celebrates the onomastics of its mother superior. They also receive a visit from the doctor, don José, an atheist but good-natured man who watches over the health of the inmates. Shortly after, the sister-in-waiting picks up a beautiful girl who has been abandoned at the doors of the convent and the doctor, despite being single, offers to adopt her legally and give the girl as a pupil to the convent. The baby will be called Teresa.