In Guanajuato, a piano teacher delays her marriage to an engineer not to let her younger sisters alone. As he is love with her voice, he is mistaken for a sister whom he marries. The teacher then goes to the capital. There she becomes part of a family of young students, who believe she is the mistress of his father, so she suffers the scorn and reproach. Over the years the parents die and she renounces to the inheritance they leave her.