When Edward Carney said good-bye to his wife, Percey, he never thought it would be the last time he'd see her.

He climbed into his car, which was parked in a precious space on East Eighty-first Street in Manhattan, and pulled into traffic. Carney, an observant man by nature, noticed a black van parked near their town house. A van with mud-flecked, mirrored windows. He glanced at the battered vehicle and recognized the West Virginia plates, realizing he'd seen the van on the street several times in the past few days. But then the traffic in front of him sped up. He caught the end of the yellow light and...