I am surprised to find it online, but you can read it here or here. This is how it begins:
"George, I wish you'd look at the nursery."I highly recommend it. I think anyone who can read this story and not rush right out and buy the book is lacking some kind of basic something that all readers should have. Either that or they don't like darker fantasy, which is possible, I guess.
"What's wrong with it?"
"I don't know."
"I just want you to look at it, is all, or call a psychologist in to look at it."
"What would a psychologist want with a nursery?"
"You know very well what he'd want." His wife paused in the middle of the kitchen and watched the stove busy humming to itself, making supper for four.
"It's just that the nursery is different now than it was."
"All right, let's have a look."
They walked down the hall of their soundproofed Happylife Home, which had cost them thirty thousand dollars installed, this house which clothed and fed and rocked them to sleep and played and sang and was good to them. Their approach sensitized a switch somewhere and the nursery light flicked on when they came within ten feet of it. Similarly, behind them, in the halls, lights went on and off as they left them behind, with a soft automaticity.
"Well," said George Hadley.
They stood on the thatched floor of the nursery. It was forty feet across by forty feet long and thirty feet high; it had cost half again as much as the rest of the house. "But nothing's too good for our children," George had said.
The nursery was silent. It was empty as a jungle glade at hot high noon. The walls were blank and two dimensional. Now, as George and Lydia Hadley stood in the center of the room, the walls began to purr and recede into crystalline distance, it seemed, and presently an African veldt appeared, in three dimensions, on all sides, in color reproduced to the final pebble and bit of straw. The ceiling above them became a deep sky with a hot yellow sun.
George Hadley felt the perspiration start on his brow.
"Let's get out of this sun," he said. "This is a little too real. But I don't see anything wrong."
"Wait a moment, you'll see," said his wife.
It has been adapted several times for both radio and television. There was a Swedish TV film adaptation released in 1983 starring Bibi Andersson and Erland Josephson.