Sin (1924)

The story of a seminary student who had an affair with a widow but is forced by his family to put an end to that relationship. The seminary student becomes a priest and one day he finds in the streets a ragged child that is the son he had with the widow. When the boy grow up, he lives together with the priest's daughter without knowing that she is his own sister. One morning, when the priest sees the two together, absolutely mad and full of pain, kills them.