Chang-rae Lee's debut novel, Native Speaker, was built around the conventions of detective fiction. But mystery-solving was never really the point: the book is an investigation into the immigrant experience of Henry Park, a Korean American and the novel's private-dick pro­tagonist, far more than it is a thriller about the local politician he is hired to follow. Similarly, the puzzle presented at the beginning of Lee's fourth novel, The Surrendered, and the private detective who is hired to solve it are really a lens through which to examine how war has damaged the lives of its characters, marking them irreparably.

Middle-aged, steely and solitary, "living an exquisitely small, circumscribed existence" in 1980s New York, June is dying of stomach cancer. But she is determined to be reunited, before she succumbs, with her estranged son Nicholas, who left home to travel around Europe nearly a decade ago and has long been out of contact with his mother. She hires a detective to find him, instructing the professional how the operation will work: she will trail Nicholas across Italy, bringing her long-absent ex-husband, Hector, in tow.

It's an exhausting journey, both emotionally and physically, but it has nothing on the one that has shaped June's life. As the novel opens, she appears as a starved and motherless 11-year-old, fleeing from the Korean war at a time when "the whole country is orphaned". Having already lost three siblings, June has to leave her little brother bleeding to death on a railway track in order to survive. She is close to death herself when she is taken in by an orphanage. There she meets Hector Brennan, a former GI who has been in a state of shock since witnessing the hideous torture of a Korean soldier, and Sylvie, a missionary's wife who helps to run the children's home - and whose own parents suffered violent ends at the hands of Japanese soldiers in occupied Manchuria in 1934.

The three become closely and darkly bound. Emotionally stunted but film-star-handsome Hector becomes Sylvie's lover, and June vies with him for the older woman's attention. Yet both are later implicated in Sylvie's death at the orphanage. Then, slightly oddly, Hector becomes Nicholas's father.

The book oscillates between June's and Hector's memories of the 1950s and their search for Nicholas, punctuating flashbacks to the events of wartime with June's inevitable decline through cancer. It is a fate she accepts with the blackest humour; she sees it as "laughably ironic" that, after the years of refugee hunger, of "the terror that was forming her into her destined shape", this tumour will lead to her dying "with her belly full".

Neither she nor Hector can leave experience behind - each has been reduced to a sort of half-person. June is mostly hard shell. Once a difficult child with an "iron gaze", she is now a cold, and therefore highly successful, businesswoman. And Hector - whose Trojan name is intended, his father tells him, as a reminder that "a man wants a son for a son, and has no use for a champion" - is almost all self-pity, sleepwalking through a small-town life, surviving hand-to-mouth (and often bottle-to-mouth) as a janitor.

Lee is a quiet and restrained writer who uses language powerfully but without pyrotechnics; the horrors that befall his characters are intensified with dense visual detail. (When June first sees the body of one of her sisters, she is "sure that she was all right, because her face was turned to her, and her eyes were open, her mouth in a faint, if somewhat confused smile. But she was dead. Both her legs were cut off. She had crawled all that way, and all her blood had run out.") The simplicity with which he describes events is often moving, though at times the characters' misfortunes - particularly those of Hector, who even in peacetime seems incapable of finding anyone to love who doesn't then die horribly - are so relentless that some of their power is lost.

It is frustrating, too, that June's life beyond her hardships - her business or her relationship with her son, for instance - feels a little sketchily drawn. Part of the problem is that while the two journeys on which the narrative hinges are both hers, Lee allows Hector to take over the story. His perfect looks and supernatural ability to drink without any obvious effect are rather clumsily symbolic. It is perhaps a continuation of the central focus on a memorable male character in all three previous novels by Lee that, in this sinuous and intertwining narrative, his male protagonist should be the one who rises to the top.

Despite its flaws, however, The Surrendered is expertly crafted - as you might expect from a novelist who is also director of Princeton 's creative writing programme. Lee slips effortlessly from one narrative thread to another and his grip on the story never loosens, so the book's 470 pages do not feel too long. Just as The Surrendered pushes the conventions of detective fiction towards sophisticated ends, so it uses migrant stories, now fashionable in literary fiction, to create a complex commentary on war.

The Surrendered
Chang-rae Lee
Little, Brown, 469pp, £12.99

Alyssa McDonald is assistant editor of the New Statesman