When the Miami Police first found Benito Que, he was slumped on a desolate side street, near the empty spot where he had habitually parked his Ford Explorer. At about the same time, Don C. Wiley mysteriously disappeared. His car, a white rented Mitsubishi Galant, was abandoned on a bridge outside of Memphis, where he had just had a jovial dinner with friends. The following week, Vladimir Pasechnik collapsed in London, apparently of a stroke. The list would grow to nearly a dozen in the space of four nerve-jangling months. Stabbed in Leesburg, Va. Suffocated in an air-locked lab in...