In the short story the setting is in the Haldey's home in the future. This family's house is filled with technology and the kids begin to love some of it more than their own parents. The protagonists are Mrs. Hadley and Mr. Hadley, the children and the technology are the antagonists.
The parents do not understand how to control the nursery and it has been showing Africa for a long time. The children deny that it was Africa and change the image when the parents check again. The parents are frightened out of the nursery and it sounds like something was trying to escape after them
After the worryingly realistic lions chasing them out the father wonder back in and finds his wallet now covered in blood. Whilst in the nursery they can see the lions eating something but can never make it out. They also hears screams that sound oddly familiar.
The children trick their parents into going in the nursery, the children lock them in. The parents scream and they are no longer heard. The parents have died and the lions turned out to have some sort of physical form
The phycologist finds the children and we can only assume he gets them some help.
The parents lives go back to normal once they die because when they were alive they weren't truly living because of the technology living their lives for them.