We have become accustomed to a fast literary turnaround in our wars recently. The troops are not back in their barracks, the guns not cold, before the first bestsellers hit the shelves. Later will come the memoirs. And as for the old wars, some catch the public imagination and some do not. The first world war and, before it, the Napoleonic wars have managed to lodge themselves deep in our consciousness, while dozens of others have failed. Perhaps that is why I felt a little surprised to see the subject of Laura Hillenbrand's new book, an epic of individual heroism and fortitude in the second world war. Weren't all those tales told in the 1950s and 60s, I wondered. Apparently not, but one must wait until the final quarter of this book to realise why the true breadth and significance of the story had to wait so long to be revealed.

Louis Silvie Zamperini was born in 1917, son of Italian immigrant parents in Torrance, California. He was a wild and wilful child, and not until he was 14 did anyone find an activity that would focus him. It was his elder brother, Pete, who thought of it: athletics. Zamperini junior roared out of the blocks and almost immediately began smashing collegiate, state and finally national records for the mile. At 19 he muddled his way into the US Olympic team for the wrong event, the 5,000m, at the very last opportunity, and within days was on a steamer heading for the 1936 Berlin Olympics. He was a cheerful and charismatic mixed-up kid who couldn't resist stealing ashtrays from the bar. He came eighth in the final, shook hands with Hitler, and went home determined to win Olympic gold for the mile at Tokyo in 1940. No one doubted it was possible. He would also be the first, said many experts at the time, to break the four-minute barrier.

Instead there was Pearl Harbor. Zamperini was drafted into the air force as a bombardier and started flying missions over the Pacific. He still kept up his training, however, and on 27 May 1943, running alone on sand in Hawaii, he clocked 4:12. He knew he could go much faster, but it was to be his last run for many years. That same day, while his plane was searching for lost airmen over the ocean, it crashed and immediately sank. So began a 47-day story of survival in which three men, reduced later to two, drifted 2,000 miles on a leaky liferaft, fought off sharks and survived Japanese air attacks.

Anyone who enjoyed Hillenbrand's previous book, Seabiscuit, will know that she has a fine line in compelling narrative. Unbroken is no different: meticulously researched and powerful. The reader, unlike the airmen, would rather the days adrift went on longer. They end, however, in grim style. Zamperini and fellow survivor are in sight of land when they are captured by Japanese forces. The Red Cross, however, is never informed and the two are declared dead.

Incarceration as a PoW, especially if taken by the Japanese, was a horrible business. Zamperini found himself beaten and humiliated with appalling regularity by one particular guard, Mitsuhiro Watanabe, nicknamed "the Bird" by the prisoners. Occasionally he was made to run against Japanese to prove their superiority. If he won, he was bludgeoned into unconsciousness. Dysentery and beri-beri wore him down, as did the guard's sadistic attacks. By the end of the war, his life was hanging by a thread.

This book shows that recollections in later life can be vastly superior to any cash-in-quick responses to dramatic events. In Zamperini, still alive at 93, Hillenbrand has discovered a man of complexity and wisdom who can look back from his great age and see the pattern of his life emerge.

The evidence of this is revealed almost as soon as Zamperini arrives back in the US in 1945 as a hero. Feted and dined, he floats on a bubble of incomprehension about his experiences. He toys with the idea of restarting a track career but soon discovers that his legs, damaged in repeated beatings and accidents, cannot do the job. He drinks. He tries investing in various wacky schemes. Spiralling downwards, he becomes obsessed with the idea of returning to Japan and killing his former tormentor. In one remarkable passage, Hillenbrand delves into the psychology of revenge. "Louis believed that only the Bird could restore him, by suffering and dying in the grip of his hands. A once singularly hopeful man now believed that his only hope lay in murder."

Here is the story that few PoW books have bothered to tell: of a man struggling to escape an inescapable past. There are no tunnels, no mass breakouts, no climbing the wire. This is an altogether more secure prison and the chief torturer is his own mind. What makes the story so fascinating is the parallel tale that Hillenbrand has unearthed, of Watanabe on the run in rural Japan after the war.

It was a Daily Mail journalist, Paul Hadfield, who finally cornered him in 1995. He was married and living as a successful insurance broker in a swanky apartment, a man not unrepentant, but not fully redeemed either. Back in California, Zamperini had managed to kick the bottle and start again. Having forgiven Watanabe, he reached some kind of inner peace and even carried the torch for the 1998 Winter Olympics in Japan. Watanabe avoided a last meeting, but that final touch of drama is not necessary for this outstanding book. With it Hillenbrand marches second world war literature right back into the spotlight.

Kevin Rushby's Paradise is published by Robinson.