The Veldt is a short horror story, part of the 1951 anthology The Illustrated Man, written by American author Ray Bradbury. It fits neatly amongst other Bradbury works which explore the peculiar relationships engendered by parenthood. Like The Small Assassin, in The Veldt two perfectly loving parents come under threat from their offspring and, forced ultimately by the blind trust of parental instinct, forfeit their lives: Bradbury's point being that although on the surface parents appear to control their children, without realising it parents are perhaps in reality controlled more by their children through instinct and, indeed, love. No-one would dare believe their children would kill them just to get their own way.
The veldt in question is a classic, dusty grassland of southern Africa, inhabited by the appropriate fauna and generated in its entirety by the Nursery, a computer-controlled playroom for the children. It's not actually real, and nor are the lions, though no-one seems to have told them that. It's not supposed to be generating a veldt, of course, so with the playroom going wrong like that, it's quite natural to venture in and investigate. Finding your partner's bloody bones on the floor ought to hint that something's not quite right, but... well, then it's too late; the kids had to do something to stop you turning the damn thing off.
It's a good story. Seek it out and read it... it will not be hard to find. Bradbury is an immensely popular writer, and for good reason.