One of the problems with being an accident reconstruction specialist, Dar was thinking as he shifted the NSX into third and took a decreasing-radius turn effortlessly, with only the throaty purr of the exhaust marking the deceleration and then the shift back up to speed, is that almost every mile of every damned highway holds the memory of someone’s fatal stupidity. The NSX roared up a low rise in the predawn glow and then growled down the long, twisty descent into the canyon some miles below.

There, thought Dar, glancing quickly at an unremarkable stretch of old single-height guardrail set on wooden posts flashing past on the outside of a tight turn. Right there.

A little more than five years ago, Dar had arrived at that point only thirty-five minutes after a school bus had struck that stretch of old guardrail, scraped along it for more than sixty feet, and plunged over the embankment, rolled three times down the steep, boulder-strewn hillside, and had come to rest on its side, with its shattered roof in the narrow stream below. The bus had been owned by the Desert Springs School District and was returning from an “Eco-Week” overnight camping trip in the mountains, carrying forty-one sixth-grade students and two teachers. When Dar arrived, ambulances and Flight-For-Life helicopters were still carrying off seriously injured children, a mob of rescue workers was handing litters hand over hand up the rocky slope, and yellow plastic tarps covered at least three small bodies on the rocks below. When the final tally came in, six children and one teacher were dead, twenty-four students were seriously injured—including one boy who would be a paraplegic for the rest of his life—and the bus driver received cuts, bruises, and a broken left arm.