Home for veteran soldier Frank Money is Lotus, a small town in Georgia he couldn't wait to escape.

As he reflects, "he hated Lotus. Its unforgiving population, its isolation, and especially its indifference to the future were tolerable only if his buddies were there with him". But his buddies are both dead, killed as they fought alongside him in Korea. One died in his arms. The other was clutching the severed limb Frank had helped him retrieve when he too died, mercifully "before the agony got to his brain".

When we first meet Frank he is in an American hospital, having been discharged from the army a year before. Physically he is well, but what he has witnessed has left an indelible, haunting mark. Only drink dulls the pain, but it also makes him unpredictable. Hence his spell in hospital, or so he assumes, because he cannot remember what brought him there.

Having conned the nurses into thinking he is asleep, Frank escapes and makes his way barefoot through the snow to the local preacher, who gives him money to start his long journey home. As the cynical reverend comments of his hospital stay: "They must have thought you was dangerous. If you was just sick they'd never let you in."

So begins this ragged young black man's return to Lotus, where he has learned his little sister is mortally ill. With no friends or lover, home for Frank is wherever Cee is. "She was the first person I ever took responsibility for. Deep down inside her lived my secret picture of myself – a strong, good me." He holds onto that thought because after what he did in the war, his self-image is tarnished, and one slowly learns why.

Frank's story is related by an unnamed third party, whom he addresses with asperity. "Since you're set on telling my story ...", "Write about that, why don't you ...", and most telling of all, "I don't think you know much about love. Or me." Thus Morrison signals the conceptual gulf between the author's recreation of what a young Korean vet must have felt like, in his own land. What doesn't need much imagination is to see that mid-1950s America was anything but welcoming for a man like him. In this era of burgeoning wealth some were enjoying the high life, but for the likes of Frank and Cee, born at the bottom of the black heap, such is the prejudice they face it might as well have been an earlier century. They don't even find comfort under their own roof. As children, "their parents were so beat by the time they came home from work, any affection they showed was like a razor – sharp, short and thin."

Prejudice comes not only from the white population but their kin. The grandmother they were obliged to stay with for some years loathed the sight of Cee and made her life miserable. As Cee reflects in the chapters she narrates: "A mean grandmother is one of the worst things a girl could have." Easily duped, she finds herself in terrible trouble, which only her brother can save her from.

The reunion of sister and brother is the thread on which this story is strung, a thick rope that pulls together Frank's past and the pair's future and ties it in a safe, sturdy knot. Morrison writes predominantly from Frank's perspective, a change of emphasis from her more typically dominant female narrators, but otherwise everything in Home will be familiar to her readers, and perhaps a little too much so.

Keen to remind people of the Korean conflict, which was as devastating for combatants as the later Vietnam War, but is now scarcely mentioned, Morrison once again conflates sweeping American politics with personal stories. These, as we have grown to expect from her, are generally grim. Of course, compared with the characters in Beloved or Paradise, Frank and Cee have it good. But that's a bit like saying a bonfire is less hot than a volcano. This novel opens with the young siblings witnessing the fall-out from an appalling crime, and in the pages that follow the abuses of characters and their neighbours, not to mention Korean civilians and soldiers, are legion.

The clarity and light-footedness of Morrison's style belies the pain she describes. Yet there is a sense, here, of Morrison working in an unusually restricted register, emotionally and artistically. The economy of brushstrokes is two-edged: evocative, but perfunctory too. What's also missing is the linguistic range and rage of earlier novels. Frank's voice is bland, almost textbook, as is Cee's. There's little trace of character in the way they speak, as if they stand as archetypes rather than individuals. And while their predicaments are engaging, brother and sister fit so neatly into the mould of Morrison's perpetual preoccupations, the theme of her entire woebegone oeuvre, it is hard to feel wholly involved with them as people. It's simpler to regard them as two new pieces on Morrison's fictional chequerboard.

That board, in fact, should have the word "home" emblazoned across it. Because over her career, from The Bluest Eye to this latest work, Morrison has been proclaiming that for her characters, whatever period they inhabit, that word has been more of a dream than a reality.