The intended moral of this story is that you shouldn't judge others by their appearance.
The story tells of a new family in town who meet Quasimodo. The parents don't like Quasimodo because he is different so they tell their two children to stay away from him. Quasimodo leaves the children gifts, unknown to the parents. While at a puppet show, the children get lost. Quasimodo approaches them, gives them bread and cheese and carries them about town to "look for their parents." Of course the parents are grateful and say they were wrong to judge Quasimodo.
In a nutshell, this book goes against everything you drill into your child. Stay away from strangers. Never accept gifts from a stranger. Never ever go anywhere with a stranger. It's hard enough to get the point across to kids...don't let this book undermine your hard work.