His followers are driven by desperate hunger. In the novel's best scene, one of its last, Esther has been terribly hurt in a car crash. Luke appears and orders an ambulance, and they rush into Manhattan toward a hospital. But someone, probably the ambulance driver, has phoned a radio station. As the news gets out, cars fall in behind the ambulance, then ahead.
Progress slows, then stops.
Luke steps out, climbs on the ambulance, shouts for a clear path.