In the fairy tale, the husband and wife fear that?

The husband and wife are afraid of rioters.... the damage that could be done to their home, and even their persons.

It was not possible to insure the house, the swimming pool or the car against riot damage. There were riots, but these were outside the city, where people of another color were quartered. These people were not allowed into the suburb except as reliable housemaids and gardeners, so there was nothing to fear, the husband told the wife. Yet she was afraid that some day such people might come up the street and tear off the plaque YOU HAVE BEEN WARNED and open the gates and stream in...