Puzzles of the Black Widowers - By Isaac Asimov Page 0,72
There has to be a reason. If there's an innocent reason that has nothing to do with his profession, what is it?"
Avalon said gently, "I take it that you yourself have never thought of an adequate reason, Mr. MacShannon."
"None, except that the envelope bore a message of some sort," said MacShannon.
"I suspect," said Rubin, "that you haven't tried thinking of what we have been calling an innocent explanation, Mr. MacShannon. Perhaps you have been too satisfied with your message theory."
"In that case, you think of an alternate reason, Mr. Rubin," said MacShannon defiantly.
"Now wait," said Halsted, "the spy thing was not Mr. MacShannon's original assumption. At first he thought that Benham was collecting postmarks - or possibly stamps, for that matter. Suppose that very first thought was correct."
MacShannon said, "Don't underestimate the FBI. I had mentioned my original thought and, on one occasion, they managed to search his apartment. There were no signs of any collecting mania of any kind. Certainly, there were no envelope collections. They told me so."
"You might have told us that," said Rubin.
"I just have," said MacShannon, "but it's not important. The chance of his saving the envelope for collecting purposes was so small that it made no sense to dwell on it. - Well, then, have you come up with some other explanation for saving the envelope, Mr. Rubin? Or any of you?"
Drake said, "It could have been a thoughtless action. People do things out of habit, all sorts of silly things. Your Mr. Benham meant to save the letter and discard the envelope and, without thinking, he did the reverse."
"I can't believe that," said MacShannon.
"Why not? It's called being absentminded," said Drake. "Later, when he found he had saved the envelope, he may have gone downstairs to recover the letter and found it gone."
MacShannon said, "A man whose career is espionage is surely not absentminded. He wouldn't last long if he were. Besides, he knew what he was doing. He read the letter and crumpled it at once and discarded it. Then he looked at the envelope thoughtfully and put it away carefully. He knew what he was doing."
"Are you sure?" said Drake. "It happened thirty-six years ago. With all due respect, you may be honestly remembering what you want to remember."
"Not at all," said MacShannon frigidly. "It was the big excitement of my life and I spent a lot of time thinking about it. My memory is accurate."
Drake shrugged. "If you insist, it's impossible to argue, of course."
MacShannon looked about the table from face to face. "Now, then, who has an alternate explanation? No collection. No absentmindedness. What else? - And no sentimental attachment for the writer. There might have been a love affair afterward, but that letter Benham discarded was clearly the first one he had received. He had just met her. And even if it was love at first sight, something he didn't strike me as subject to, he would have kept the letter, not the envelope."
There was silence around the table and MacShannon said, "There you are! It's bothered me for all these years. What was there about the envelope that defeated the FBI? I guess I'll just have to keep on wondering for the rest of my life."
"Wait," said Avalon, "the communication, if there was indeed one, may have been on the first envelope only, the one he saved and the one that the FBI presumably never saw. All the others may have been clean and irrelevant."
MacShannon's little beard quivered at that. "I'll leave it to Mr. Trumbull," he said. "He said he was with counterintelligence. Does a conspirator of some sort give up a method of communication once it has been proven successful?"
Trumbull said, "It's not a cosmic law, but successful gambits are not lightly abandoned, it's true. However, it might no longer have been particularly successful. That envelope he kept may have just happened to be the last of a line of such things that was using a technique that had grown risky. It could then have been abandoned."
"Might! May have! Could have been!" said MacShannon, his voice rising to a squeak. "We have two actual facts. The man was a spy. The man did keep an empty envelope. Let's find an explanation as to why a spy should keep an empty envelope, an explanation that isn't pure speculation."
Again there was silence about the table and MacShannon smiled sardonically and said, "There is no such explanation, except that it bore a message."