"First, I'll tell you about the robbery our parents committed. Then about the murders, which happened later." So, tantalisingly, begins Richard Ford's seventh novel, Canada, a big book that takes its time to tell the story of how 15-year-old Dell Parsons's life was temporarily derailed by a single, spectacularly uncharacteristic act by his mother and father: a barely planned and ineptly executed bank robbery.

Like Ford's breakthrough novel, The Sportswriter, first published in 1986, Canada is essentially about the consequences of a sudden tragic rupture in the fabric of an ordinary family life. It marks a distinct shift in style, though, from the dense, discursive sentences that characterise the Frank Bascombe trilogy  The Sportswriter, Independence Day and The Lay of the Land. In Canada, the writing is leaner, tighter and less concerned with the inner significance of everyday things. Ford can still stretch a sentence, often beautifully, to paragraph length, but his writing is much more straightforwardly descriptive than it has been for a long time.

In a way, this is a return to the so-called "dirty realism" of earlier books like A Piece of My Heart and The Ultimate Good Luck, though Canada is much more epic in its scope and more confidently slow and deliberate in its telling. The narrator, Dell Parsons, now a retired English teacher, looks back with a kind of bemused detachment on the unlikely events that unmoored him from his ordinary life and pitched him headlong into an uncertain future. From the start, it is apparent that this is someone trying to make sense of the past, and the leisurely way the story unfolds reflects the narrator's need to be sure-footed in his piecing together of events. One of the consequences for the reader is that the narrative, which is meticulous in its re-creation of period details  the makes of cars, the cut of clothes, the slow, repetitive rhythms of small-town life  takes a long time to catch fire. Even the bank robbery, when it is finally described almost one hundred pages in, is reconstructed in low-key fashion, its outcome a foregone conclusion. What is important here is not the event, but its long aftermath.

Canada is divided into three untitled parts. The first, concerning the crime and its immediate fallout, is set in the mid-to-late 1950s in Great Falls, the Montana town that Ford has used as a backdrop in some previous stories. The second describes Dell's clandestine flight to an even more downbeat town just over the border in Canada and his new life as a kind of odd-job boy for a mysterious American fellow exile, Arthur Reminger. When Reminger's own dark past catches up with him, Dell becomes an unwitting accomplice in a ruthlessly executed killing and is spirited away once more, this time to the care of another stranger 500 miles away in Winnipeg. Of that long interlude we are told nothing, and the third and final part of the book, a short postscript set in the recent past, mostly concerns Dell's visit to his estranged sister, Berner, who is living  and dying from a terminal illness  in Minneapolis.

What is of most interest to Ford is not the crimes themselves, but how they shape Dell's life and his way of being in, and responding to, the world. Throughout, Dell's calm and measured voice suggests someone not so much damaged as detached. There are hints here and there of the "dreaminess" that infects Frank Bascombe's life in the wake of his son's death and of his grief-driven tendency to endlessly circle, but not quite close in on, the meaning of that cruel loss. There are several moments in Canada where Dell seems on the verge of some great epiphany, but arrives instead at a smaller understanding of the strange trajectory of his younger life. Having had, as his mother predicted, "thousands of mornings to wake up and think about this", Dell has finally connected his father's decision to rob a bank to his experience of active service in the second world war, a life-changing interlude that his father has no way of describing, much less understanding.

"When he returned from the theatre of war and from being the agent of whistling death out of the skies" writes Ford in one of those luminous passages of reflection that have become a kind of signature, "he may have been in the grip of some great, unspecific gravity, as many GIs were. He spent the rest of his life wrestling with that gravity, puzzling to stay positive and afloat, making bad decisions that truly seemed good for a moment, but ultimately misunderstanding the world he'd returned home to and having that misunderstanding become his life."

In a roundabout way  is there any other way in a Richard Ford story?  the faults of the father are passed on to the son. The older Dell, though, who guides us though the strange jolts in his life calmly, step by step, does not so much misunderstand the world as keep it at a safe distance, so justifiably wary is he of the sudden, cataclysmic turn it may take. This strategy seems to have worked and, by the end of the book, he seems a remarkably accepting, even contented, individual.

By then, we have found out that his parents are dead, his mother by her own hand, and that his long-lost twin sister, whose life has been altogether more blighted by the robbery than his, has not long to live. That he has survived and, to a degree, thrived, is down to some degree to his passivity and to his acceptance of things as they have turned out. He refuses throughout to blame his parents or to dwell too deeply on the big question of what might have been. Instead, his philosophy is best summed up by the wisdom he passes on to the students in his writing class, which manages to be both matter-of-fact and poetic: "I believe in what you see being most of what there is and that life's passed on to us empty. So, while significance weighs heavy, that's the most it does. Hidden meaning is all but absent."

Perhaps that is the abiding subject of all Richard Ford's work. Here, though it is broached by way of some uncharacteristically violent interludes, it resounds with a newfound clarity. A surprisingly different kind of great Richard Ford novel, then, and one that casts its spell very slowly and with a steady cumulative power.

"Children know normal better than anyone," says Dell Parsons, the narrator of Richard Ford's luminous and utterly forlorn new novel, and certainly Dell when he was a child knew far better than most what a normal life, especially a normal American life, is likely to turn out to be. The opening sentences of the book, which are bound to go straight into the collective literary memory, tell us what he, and we, are in for: "First, I'll tell about the robbery our parents committed. Then about the murders, which happened later."

The year is 1960, and the Parsons family  father Bev, mother Neeva, and 15-year-old Dell and his twin sister, Berner  are settled, just about, in the city of Great Falls, Montana, having moved there four years previously. Bev, a good ol' boy from Alabama, had been an air force bombardier who saw action in the Philippines and Osaka, "where they rained down destruction on the earth". Having left the service, he works as a car salesman and then gets involved in a beef-smuggling racket with a local band of Indians. Neeva, short for Geneva, "a tiny, intense, bespectacled woman with unruly brown hair, vestiges of which ran down her jawline", is Jewish, and has literary pretensions, or longings, at least. She and Bev are an archetypical American married couple of the time, who just happen to become bank robbers.

"While from a distance," Dell writes, "it may seem that our parents were merely not made for one another, it was more true that when our mother married our father, it betokened a loss, and her life changed forever  and not in a good way  as she surely must've believed." At a certain level, and although Dell specifically denies it, Canada is a study of that sense of loss, which was, and is, pervasive in American life  consider today's Tea Party movement and its members' plaintive wish to "take back" the country from the mysterious forces that somehow stole it from them. The Parsons, man and wife, are not particularly unhappy together, just discontent and uncertain, so that Dell can honestly say that to him and his sister "life in our house seemed normal". Normal: there is that word again.

Dell writes of his father that when he came back from the war in 1945 "he may have been in the grip of some great, unspecified gravity, as many GIs were. He spent the rest of his life wrestling with that gravity, puzzling to stay positive and afloat, making bad decisions that truly seemed good for a moment, but ultimately misunderstanding the world he'd returned home to and having that misunderstanding become his life."

The portraits of Bev and Neeva are masterly. These are perfectly ordinary people who get dragged down by the force of that "great, unspecified gravity" and, still gamely in pursuit of "normality", turn to desperate measures to solve the difficulties of their lives. Inevitably, the beef-smuggling scheme goes wrong, the Indians threaten serious violence, until Bev and Neeva can see no way out of their predicament other than to rob a bank and use the proceeds to pay off their ill-gotten debts. That plan also goes awry, of course, and one day the police arrive and the couple are put in handcuffs and taken away, with no immediate arrangements in place for the care of the twins.

The chapters devoted to the arrest of the parents and how the children cope with the calamity form the beating heart of the book. What makes these pages so powerful is the unrelenting control that Ford exerts over the style and pace of the writing. "You'd think," Dell observes, "that to watch your parents be handcuffed, called bank robbers to their faces and driven away to jail, and for you to be left behind might make you lose your mind. It might make you run the rooms of your house in a frenzy and wail and abandon yourself to despair, and for nothing to be right again. And for someone that might be true. But you don't know how you'll act in such a situation until it happens. I can tell you most of that is not what took place, though of course life was changed forever."

It took this reader a little time to become accustomed to the measured, downbeat tone of Canada. In the superb trilogy of novels centred on the character of Frank Bascombe  The Sportswriter, Independence Day and The Lay of the Land  Ford developed an idiosyncratically playful, slyly dandified voice that owed as much to the great European stylists as it did to Emerson and Twain. In this new book, he writes with deliberate flatness, eschewing stylistic flourishes  except when describing North American landscapes  so that Dell speaks in the cadences of a permanently damaged spirit. Listening to him, sentence by careful sentence, is like watching a car-crash survivor making his way along a hospital corridor, step by careful step. His voice, at once muffled and clear, is remarkably resonant, and devastating in its directness, as when he almost casually describes how he and Berner engage in a brief bout of consolatory incest, or when he remarks of his father, "In truth, we were never close, although I loved him as if we were."

In the middle, the book divides abruptly, and at first it seems that there are two novels here that have been spliced into one. This is a feat of great technical daring, which Ford just about pulls off. As part two opens  "Life-changing events often don't seem what they are"  Bev and Neeva are in jail awaiting trial, Berner has walked off into the wide American afternoon, and Dell is being driven by a friend of his mother's, Mildred Remlinger, across the border to Canada, where he will be left in the care, if that is the word, of Mildred's brother Arthur, who owns a run-down hotel in Fort Royal, a dingy town outside Saskatchewan. Before he encounters Arthur, however, Dell finds himself left to the untender mercies of Arthur's henchman Charley Quarters.

This pair are extraordinary creations, at once enigmatic and vividly alive on the page. Arthur, handsome, finely dressed, urbane, is a man with a past who knows that "bad things were coming to him". "Absence," Dell tells us, "was his companion in life," and he needs Dell to be for him a "special son" who will "do what sons do for their fathers: bear witness that they're substantial, that they're not hollow, not ringing absences". In contrast to his boss, Charley Quarters is a feral creature, a hunter who shoots anything that moves, dyes his hair and on occasion wears lipstick.

Here we seem to be in the territory of Robert Stone or Cormac McCarthy, or on its borders, at least. However, the inevitable violence when it comes is presented in the same low-key manner that is maintained throughout the book. "I remember very well how fast the shooting and the killing took place. There were no dramatics to it, as in movies. It happened at once  almost as if it didn't happen. Only then someone's dead." These violent acts are of far less moment to Dell than the struggle he must engage in to hold himself apart from the mayhem and not allow his spirit to be damaged by it. Here, once again, we hear the enduring refrain: "Through all these memorable events, normal life was what I was seeking to preserve for myself." But what, by now, would constitute normal life?

Canada is a superlatively good book, richly imagined and beautifully fashioned. Although it is too early to do so, one is tempted to acclaim it a masterpiece. It catches movingly the grinding loneliness at the heart of American life  of life anywhere. As the narrative makes its measured progress, the sadness steadily accumulates, a weightless silt that gets under the eyelids. The final encounter at the close of the book between Dell and Berner is one of the most tenderly drawn scenes in modern literature, and could only have been written by a writer of Richard Ford's empathy, insight and technical mastery.

 John Banville's Ancient Light will be published in July by Viking.