Sometimes a picture is worth more than a thousand words. Sometimes it can change a man's life and even, for good or ill, the course of international politics. It's hard to argue against that in the case of Paul Watson's famous 1993 photo of a dead American soldier dragged in triumph by a howling mob through Somalia's capital of Mogadishu. The shocking image of Staff Sgt. William Cleveland's mutilated corpse was emblazoned across U.S. media. Domestic opinion turned hostile, and President Clinton immediately abandoned the pursuit of Somali warlord Mohammed Aideed -- the mission that had cost Cleveland his life -- and set an early date for the withdrawal of troops from the war-torn nation. The next year, the politically potent photo was instrumental in keeping American forces out of Rwanda while genocide raged. In 1996, Osama bin Laden cited the incident as proof that the U.S. was unable to stomach casualties: when "one American was dragged in the streets of Mogadishu you left; the extent of your impotence and weaknesses became very clear."

But no individual was more affected by the click of the camera's shutter than Watson himself. The picture is the focal point of the Toronto-born foreign correspondent's scarifying memoir, Where War Lives(McClelland & Stewart). His book is a kind of literary car wreck, almost impossible to turn your eyes from. Beautifully written and pitilessly honest about the author's life and line of work -- and the role of the West in the world's recent bloodbaths -- the narrative is propelled by an apocalyptic mix of anger, guilt and post-traumatic shock. "I wanted to be as real and as truthful as possible," Watson, 48, says over the phone from his home in Jakarta where he's South Asia bureau chief for the Los Angeles Times, "and the reality of our times is deeply depressing." His book is an attempt to "restore some of the honour that I stole in that second when I pushed a button."

For most of his story Watson is not haunted by Cleveland as much as hag-ridden by him, to the extent that when an Iraqi mob closed in on him 10 years later, the first thought in Watson's mind was not "Am I going to die?" but "Is he coming to take me now?" On Oct. 3, 1993, when the First Battle of Mogadishu -- made famous by the book and film Black Hawk Down -- began, Watson, then working for the Toronto Star, was already in bad shape. In July, after an abortive American air strike against warlord Aideed killed 70 Somalis, a mob had murdered four journalists trying to report the catastrophe; there were few foreign reporters left in the Somali capital.

Watson was hanging in, working his way through most of a case of beer daily, essentially indifferent to whether he lived or died, sharing the Somalis' hatred of the armed airships that invulnerably dealt death from the sky, and incensed with the lies and evasions daily offered by UN and U.S. military spokesmen. When Aideed's militia finally managed to down a Black Hawk in September, Watson reached the site and reported scenes of women parading charred hunks of human flesh on sticks. But the Pentagon blandly denied it, claiming to have recovered all remains. Watson, by then the only Western reporter left with a camera, was determined to secure proof next time.

On the morning of Oct. 4, after fierce nighttime fighting had killed 18 Americans and more than 600 Somalis, many of them women and children, a hungover Watson listened to rumours of a dead American being paraded in the streets. Riding roughshod over the fears of his Somali helpers, Watson went looking, eventually finding a crowd of 200 people torn between showing off their trophy and attacking another Westerner.

The mob parted, letting him see Cleveland's corpse even as individuals kept approaching, kicking, beating or spitting on the lifeless flesh. The moment of choice, when Watson "had to decide whether to steal a dead man's last shred of dignity," still lives in his mind. As he raised the camera, the world went quiet and he heard a voice: "If you do this, I will own you forever." Watson pressed the shutter.

"My psychiatrist says it was my superego talking," Watson says matter-of-factly, "but I have no question in my mind that it was Cleveland speaking to me, no question at all." Nor that his world, already crumbling, would ever be the same. The following May, as the guilt deepened, Watson was in New York, accepting the Pulitzer Prize for news photography. There he encountered South African Kevin Carter, two years younger, winner for feature photography for his shot of a vulture waiting for a starving Sudanese girl to die. Carter was harassed -- in a variant of shoot-the-messenger response -- by people who ignored the fact the photo was taken in a refugee camp staffed by overwhelmed aid workers, and wanted to know what Carter had done to help the girl. His answer, that he sat under a tree, lit a cigarette and wept, didn't satisfy his questioners. And perhaps not him. Two months after the Pulitzers, Carter, strung out on drugs and messing up his assignments, killed himself.