A child had died in the neighborhood. A four-year-old girl called Molly. The day it happened, there had been snow. Molly and her mother, Sarah, went out to shovel the front steps. They took the dog, an eager, young chocolate Labrador. The snow was heavy and wet, the kind that packs well. Molly had just learned to make snowballs. Afterwards, the neighbors would point to the steep slope of the yard, the tiered garden beds, the rows of shrubbery wrapped in misshapen bundles of burlap and twine. There was no space to play, and the child was always running around in the boulevard. Molly had hurled a snowball into the street and followed as the dog went after it. Neither of them noticed the car, but Sarah, hearing the crunch of tires in snow, looked up from the shovel and said, “Molly, stop! Car!” The little girl halted, teetering at the curb, still laughing at the Labrador as it scrambled to find the snowball in the white slush of the road. The car rolled forward …