Realist melodrama set in Zurich. In the old town district, people are concerned about Mäni, the child of a toilet attendant, who is growing up without a father. Postman Jucker appeals to the boy's conscience and protects him from unjustified accusations. After Mäni's mother dies, Jucker, who has become the child's guardian, takes Mäni into his home. Mrs. Jucker does not accept the boy and accuses Jucker of forgetting their own deceased child. Mrs. Jucker flees to her sister's house. Mäni also runs away.