It was a summer morning in 1982 when soldiers ravaged the village of Chupan Ya, raping and killing women and children. Twenty-three victims are said to lie in the well where, twenty years later, Dr. Temperance Brennan and a team from the Guatemalan Forensic Anthropology Foundation now dig. No records were kept. To their families, the dead are "the disappeared."

Forensic anthropologist for the medical examiners in North Carolina and Montreal, Tempe is in Guatemala for a month's service to help some families identify and bury their dead. She digs in a cold, damp pit where she finds a hair clip, a fragment of cloth, a tiny sneaker. Her trowel touches something hard: the hip of a child no more than two years old.

It's heartbreaking work. Something savage happened here twenty years ago. The violence continues today. The team is packing up for the day when an urgent satellite call comes in. Two colleagues are under attack. Shots ring out, and Tempe listens in horror to a woman's s...