So, there’s this cranky old man or woman in the neighborhood. The house is creepy looking and all the kids are afraid of this person. Yes, traditional sounding story, right?
Of course the kids are playing ball and the ball goes over the fence into cranky person’s yard. After some debate they decide to all go in search of the ball.
What they discover on the other side of the fence is a magical, mystical world. The cranky old man or woman is caring for and protecting unicorns and fairies.
The kids soon learn the reason the person acts so cranky is to keep people scared off, so he/she can protect these wonderful creatures.
The story could go on that he/she befriends the kids and needs to enlist their help against some evil plot.