But the business of these computers is not business. It is spying. Some of the brute force of all this computing power is used by cryptologists to. break coded material. Some is used to translate messages intercepted in a foreign language into English. But by far the lion’s share of the massive computer complex is used to analyze signals and conversations picked up by the NSA’s gigantic system of signal intercepts.

Like a giant combine harvesting the kernels from a field of grain, the NSA scans billions and billions of messages that travel the world’s airwaves every second: spy satellites comb the earth below for telemetry signals from Russian or Chinese missile launches; airborne spy planes snare conversations between MiG fighter pilots and their ground control; even the car telephone calls made by Kremlin officials as they travel to work somehow find themselves caught in the NSA’s broad net.

But more than just the conversations of America’s enemies fall within the NSA’s area of concern, for the agency’s job is also to determine who among the citizens of the United States is an enemy previously unidentified. To this end, the NSA’s antennae intercept telephone calls, cable messages, and telexes made by ordinary individuals.

An internal NSA investigation would later reveal that Seth Ridgeway’s telephone call to Jacob Yost originated from a GTE pay telephone on the mezzanine level of the international terminal at the Los Angeles International Airport. The signal quality of the telephone transmission was substandard, similar to that originating from the crude telecommunications systems found in the Third World.

Ridgeway’s call was switched over to long-distance ground lines leading to COMSAT’S Jamesburg, California, earth station. All of the satellites’ available circuits were occupied at the time, so the COMSAT switching computer connected the call to transcontinental land lines, where it eventually found an unoccupied circuit at TAT 6 (Transatlantic Cable 6) in Green Stratton, Rhode Island. From here it made the 3,400-mile trip to the coast of France, emerging near Deauville, where its care fell into the hands of the French PTT—Poste, Téléphone, et Télégraphe. From the coast, the call was beamed via microwave to a switching center east of Paris. There the PTT computer passed the call via the primary land trunk cable to Switzerland’s PTT computer, which then routed it to Zurich. At Zurich a series of computer switches finally located Jacob Yost’s telephone and caused it to ring.

During this intricate process, Seth only half listened to the minute or so of clicks, clacks, thunks, and echoes in the telephone’s earpiece. He was thinking more about what he would say to Yost than about the static on the line.

The conversation seemed innocuous by any standards. Seth wanted to speak to the old man, who was out. What did it concern, the old man’s son asked. A painting by a man named Stahl they had framed decades ago, a picture of an Austrian meadow called The Home of the Lady Our Redeemer. The son was not familiar with it, but he would check with his father, and, in any event, the old man would welcome a visit by Herr Ridgeway.