WE'VE ALL HAD the wide-awake nightmare, a theatrical fantasy that teases and taunts while saving us from a day of tedium and despair. Such fantasies have the power to shock us out of humdrum security. A routine trip to pick up the children at the pool becomes a fantasy of rescuing a drowning child; a baby lying peacefully asleep in the late afternoon inspires a fantasy of a kidnapping at sundown. We derive pleasure from these ghoulish, often comic heroic fantasies because we know that such things don't really happen to nice people like us.

But sometimes they do. The narrator in Mom Kills Kids And Self , a first novel, is a suburban Walter Mitty who walks on the wild side of a perverse imagination and is trapped in a tragic vision come true.

His tale opens on a Friday night: "When I arrived home from work I found my wife had killed our two sons and taken her own life."

And so ends for the husband the "thumping sense of dread . . . that something terrible was going to happen." It also dissolves his persistent daydreams of family fires, kidnappings and automobile accidents. No longer must he commandeer taxis, jump over turnstiles, leap down stairwells, hurl himself against the doors of moving subway trains, all the while setting speed records to say to any law abiding citizen who cares: "My family needs me."

Strange events flash before his mind, with instant replays of the Friday night massacre, as though by seeing it again he can bring his wife and children back to life. He struggles in vain to rewrite his own history, talking to the dead bodies in ways he never spoke to the people who had lived in those bodies.

But too late: Too late to be present at the birth of his oldest son, the difficult one with brain damage; too late to appreciate the younger son, to praise him for walking on schedule, to forgive him for being normal; too late to erase his infidelities, to see the schizophrenic symptoms in his wife's behavior, to tell her all the reasons why he loved her.

Because he believes that "evil happens in retrospect, or else we'd be wise enough to avoid it," he at last finds himself evil, and thus as guilty of murder as if he had slain his wife and sons himself.

His is the story of a guilt ridden, grief stricken husband whose narrative juxtaposes surreal situations with photo-album images of family life, pictures that will be broken into the thousands of tiny dots that make up the grainy photographs in the newspaper. He flogs himself with details that deprive him of the anonymity of his existence, but do nothing to relieve him of the banality of his own evil.

No one in this tragic family is identified by name. The adult victim was a full-time mother, the sons were seven and four years old. The narrator-husband is a "research-analyst," a man who can measure "America's innermost feelings" but who doesn't notice those of his wife and sons. He is a commuter, a contemporary Everyman who is summoned by tragedy to account for his life.

But when he examines each deposit and withdrawal slip in his spiritual savings account he finds only a few nickels and dimes. Like his medieval counterpart, he seeks refuge in what is familiar. Instead of friend or kin, he conjures Kojack, a television detective, whom he imagines will smell the rat in the shadow of his suburban life and furnish an answer to the nagging questions which he was always afraid to ask.

But this is no ordinary detective story. Clues won't solve the crime. Murder is metaphor, and the mystery is the human condition. Saperstein probes the personal experiences of one family in order to expose the paradoxes in life itself. The real mystery is "whether or not misery is the natural, normal state of man."

With fascinating versatility, Saperstein shows us alternating views of the same incident, first tragic, then comic. Scenes in the novel, like the people who act out these scenes, are ambiguous, sometimes awesome, and frequently absurd.

Mom Kills Kids and Self grips with social-psychological insights, and throbs with a spare poetic power. Both funny and frightening, it inspires pity, fear, and terror. Saperstein occasionally throws out transparent and cliched feminist arguments to interpret tragedy, but only occasionally, and he does not dwell on fashionable explanations. With bold, vivid strokes, he dissects complexity of character and dramatizes the craziness which lurks within us all.