In 1969, a young freelance reporter named Seymour Hersh got an interesting tip. On an early spring day the previous year, it seemed, something had taken place in a Vietnamese village that exceeded even the brutal bounds of the Vietnam war.

Hersh got on the case. He began travelling the country in search of soldiers from the company mentioned in the tip-off. He wound up tracking down and speaking to more than 60 of the men, including platoon leader William Calley, who was living on the army base in Fort Benning, Georgia. Hersh and Calley, a diminutive, 26-year-old college drop-out from Miami, spoke for several hours. Then they went to buy steaks, beer and bourbon at the local grocery store, made dinner at Calley's girlfriend's apartment, and talked some more. The story Hersh strung together from that conversation and others was not so convivial: on March 16 1968, Calley's men stormed into the village of My Lai, in South Vietnam, expecting to find members of a Viet Cong battalion that had taken part in the recent Tet Offensive. The Americans found no enemy soldiers. Instead, they shot, stabbed and gang-raped the village's elderly, women, children and babies. A day later, they burned the place down. Hundreds of people were killed.