On to Kiev. His course changed at Dnepropetrovsk, from northeast to northwest, for the next two hundred fifty miles. At Kiev, the river changed course again, heading north. Three hundred and fifty miles farther on, at Smolensk, he was heading almost due east. It had not been an easy trip. At night, he had surfaced to get his bearings and to recharge the air tanks. Several times, he had had to take to the land, using the caterpillar treads on the little machine, because of obstacles in the river. At the end of the ninth day, he was still one hundred eighty miles from Moscow, but, at that point, he got out of the submarine and prepared himself for the trip overland. When he was ready, he pressed a special button on the control panel of the expensive little craft. Immediately, the special robot brain took over. It had recorded the trip upstream; by applying that information in reverse--a "mirror image," so to speak--it began guiding itself back toward Istanbul, applying the necessary corrective factors that made the difference between an upstream and a downstream trip. If it had made a mistake or had been discovered, it would have blown itself to bits. As a tribute to modern robotics and ultra-microminiaturization, it is a fact that the little craft was picked up five days later a few miles from Istanbul by the U.S.S. _Paducah_. By that time, a certain Vladimir Turenski, a shambling not-too-bright deaf mute, had made his fully documented appearance in Moscow. * * * * * Spies, like fairies and other such elusive sprites, traditionally come in rings. The reason for this circumstructural metaphor is obscure, but it remains a fact that a single spy, all by himself, is usually of very little use to anybody. Espionage, on any useful scale, requires organization. There is, as there should be, a reason for this. The purpose of espionage is to gather information--preferably, _useful_ information--against the wishes of, and in spite of the efforts of, a group--usually referred to as "the enemy"--which is endeavoring to prevent that information from getting into other hands than their own. Such activities obviously imply communication. An espioneur, working for Side A, who finds a bit of important information about Side B must obviously communicate that bit of information to Side A or it is of no use whatsoever. All of these factors pose complex problems. To begin with, the espioneur must get himself into a position in which he can get hold of the information he wants. Usually, that means that he must pass himself off as something he is not, a process which requires time. Then, when he gets the information he is after, he must get it to his employers quickly. Information, like fish, becomes useless after a certain amount of time, and, unlike fish, there is no known way of refrigerating it to retard spoilage.