The Veldt
A futuristic nursery room, controlled by their children's thoughts, wreaks havoc on a husband and wife.
"As for the nursery, thought George Hadley, it won't hurt for the children to be locked out of it awhile. Too much of anything isn't good for anyone. And it was clearly indicated that the children had been spending a little too much time on Africa. That sun. He could feel it on his neck, still, like a hot paw. And the lions. And the smell of blood. Remarkable how the nursery caught the telepathic emanations of the children's minds and created life to fill their every desire. The children thought lions, and there were lions. The children thought zebras, and there were zebras. Sunsun. Giraffesgiraffes. Death and death."