What's a summary of "Once Upon a Time"?

"Once Upon a Time" begins with the author somewhat irritated by a presumption that she "ought" to write a children's book. That night, she awakens from a sound sleep, disturbed by something unknown, and she fears that it is a burglar. This is where historical context is needed: Gordimer lived in South Africa during apartheid and frequently wrote about how the nation could work toward a post-apartheid future. Violence was not uncommon; she fears that she will be murdered, a fate that has befallen neighbors.

She realizes that the sound was not derived from footsteps, but was rather a result of the mine underneath her house that shifts the structure around her. Still, she is unable to sleep, and so she tells herself a bedtime story. 

There was a family who was living "happily ever after" in a suburb: a husband, a wife, and their small son. They began to follow the advice of the husband's mother, an "old witch," who warned them not to take people in off the street. They acquiesced and implemented security measures such as insurance, a gate around the pool, and a neighborhood watch program which came with a YOU HAVE BEEN WARNED sign to be hung on the gate. The sign also contained a picture of a masked burglar, and it is said that because it is masked, it could not possibly be racist.

Soon, the family no longer felt that this was enough and riots outside the suburb convinced them to install electronically controlled gates with an intercom system. The maid was still concerned about the security, and so they had burglar bars installed on all the windows and put in sensitive burglar alarms. The alarms were not particularly useful: they were so sensitive that the cat could set them off, and thieves used the cover of the noise to break into the houses.

The wife stopped supplying the people outside the gates with food after the housemaid warned her against it. They decided to build the wall higher, and the mother-in-law supplied them with the extra bricks and a book of fairy tales for the son. Eventually, they decided to add security measures to the top of the fence, and chose a coil of vicious wire to be installed by a company called Dragon's Teeth.

One day, inspired by the tale of Sleeping Beauty, the little boy decided to make his way through the thicket of thorns. He took a ladder over to the wall and climbed into the razor-sharp coil of wire. It is heavily implied that he died, as the parents, the gardener, and the housemaid hacked the "bleeding mass of the little boy" out of the security wire with saws.