As the California Limited sped southward through the long, flat San Joaquin Valley, Thomas O'Roark struggled to stay awake. One moment he was scrunching around in the unrelenting mohair seat, his head bumping against the mahogany window frame, trying to get comfortable; the next he was sitting up massaging the bullet wound in his leg, attempting to ease the pain. When the train lurched through a switch block, he rubbed his eyes awake and leaned forward...