"I think that would entirely depend on the man's temperament, professor."

"That may be true, but we have also got to consider the man's character. Sir Joseph's standing is very high."

"Sudden temptation or necessity may subvert the highest character," I answered. "You know that as well as I do. When I questioned Sir Joseph about his papers his manner seemed curious, as I have said. He at once declared that he had no part in any Government secret or mysterious society, gratuitous information, you understand, not in answer to any direct question of mine, showing that the ideas were in his mind. Why? The explanation would be simple if he were the burglar of his own papers."

"I admit the argument is sound, Wigan, but it does not creep into my brain with any compelling influence. There is a link missing in the chain somewhere," and he looked at Zena.

His often-repeated statement that she helped him by her questions had never impressed me very greatly. When a mystery was cleared up, it was easy to say that Zena had put him on the right road, and I considered it a whim of his more than anything else. Still I am bound to say that her seemingly irrelevant questions often had a curious bearing on the problem. It was so now.

"You do not seem interested in the broken box of counters?" she said, turning toward her grandfather.

"I wonder, Wigan--is that the clew?" Quarles said quickly. "It creeps into my brain."

"The counters were in a heap," I said.

"As if they had fallen out of the box when it was broken?" asked Quarles.

"No, that would have scattered them more. They were round, and might have fallen over after having been put one upon another as one gathers coppers together when counting a number of them. Sir Joseph picked them up and put them on the writing-table while he was talking to me."

"Did that strike you as significant?" asked Quarles.

"I cannot say it did. The floor was covered with things, and I fancy they happened to be in his way, that was all."

"They are significant, Wigan, but I cannot see yet in which direction they lead us. We must wait; for the moment there is nothing to be done."

I had become so accustomed to Quarles jumping to some sudden conclusion that I was disappointed. I think I was prepared to find him a failure in this case. Naturally I was not idle during the next few days, but at the end of them I had learnt nothing.

Then the unexpected happened. On consecutive nights two doctors'

houses were burgled. The first was in Kensington. Dr. Wheatley had taken some part in local politics which had made him unpopular with certain people, and he was inclined to consider the burglary one of revenge rather than intended robbery. Nothing had been stolen, but everything in his room was in disorder, and a small and unique inlaid cabinet with a secret spring lock had been smashed to pieces. Several cigarette-ends were on the floor.

The second was at Dr. Wood's in Ebury Street, an eminent surgeon, and the author of one or two textbooks. He had several cabinets in his room containing specimens, and everything had been turned on to the floor and damaged more or less. In fact, although nothing had been taken, the damage was considerable. On the night of the burglary Dr.

Wood was away from home, only servants being in the house. The cook, suffering from faceache, had been restless all night, but had heard nothing. It seemed, however, that the burglar must have heard her moving about and had been prepared to defend himself, for a revolver, loaded in every chamber, was found on one of the cabinets. Apparently, having put it ready for use, he had forgotten to take it away.

The doctor was furious at the wanton destruction of his specimens, and, being irascible and suspicious, fancied the revolver was merely a blind and that the culprit was some jealous medical man. Again there were cigarette-ends among the debris.

As soon as possible I went to Quarles and was shown into the empty room.

"The unexpected has happened," I said.

"No, no; the expected," he said impatiently, and he pointed to a heap of newspapers. "I've read every report, but tell me yourself--every detail."

I did so.

"The same brand of cigarettes?" he asked.

"No, but all cheap American ones."

"One man trying to give the impression that he is several. You still think that? Nothing has happened to make you change that opinion?"

"No, I hold to the one man theory."

"And you are right," he snapped. "I admit I might not have got upon the right track had you not made that discovery. It was clever, Wigan."

"It did not seem to help you to a theory," I answered.

"True. But it made me ask myself a question. Had the thief found what he was looking for? Much depended upon the answer. If he had, I saw small chance of elucidating the mystery. I might have propounded a theory, but I should have had no facts to support it.

"Indeed, had I theorized, then my theory would have been wrong. If the thief had not found what he wanted, he would continue his search, I argued. For some reason he connected Sir Joseph Maynard with the object of his search, and, when he tried again, we stood a chance of finding the link in the chain we wanted. It might implicate Sir Joseph, it might not. That is why I said we must wait. The thief has tried again--twice. Now, what is he looking for?"

"Presumably something a doctor is likely to have," I said.

"And not silver, nor money, nor papers, nor----"

"Nor counters, I suppose," I interrupted.

"Not precisely," said Quarles. "But those counters have inspired me.

They crept into my brain, Wigan, and remained there. Whatever it is the thief is seeking for, he is desperately anxious to obtain it--witness his two attempts on consecutive nights."

"You forget that days have elapsed since Sir Joseph's was broken into."

"Forget? Nonsense!" said the professor sharply. "Should I be likely to forget so important a point? It means that opportunity has been lacking. More, it means that any doctor would not do, only certain medical pract.i.tioners. And that is where the counters help me--or I think they do."

"How?"

"Call for me to-morrow morning; we are going to pay a visit together.

We may be too late, but I hope not. That revolver left in Dr. Wood's house rather frightens me."

"Why, particularly?"

"It proves that the thief will use violence if he is disturbed, and that he is a desperate man. I should say he will grow more dangerous with every failure."

It was like Christopher Quarles to raise my curiosity, and then to leave it unsatisfied. It was his way of showing that he was my superior--at least, it always impressed me like this. No man has ever made me more angry than he has done. Yet I owe him much, and there is no gainsaying his marvelous deductions.

He made me angry now, first by his refusal to tell me more, and then by his patronizing air when I left the house.

"You are clever, Wigan, very clever. You have shown it in this case.

But you lack imagination to step out as far as you ought to do.

Cultivate imagination, and don't be too bound up by common sense.

Common sense is merely the knowledge with which fools on the dead level are content. Imagination carries one to the hills, and shows something of that truth which lies behind what we call truth."

I found him ready and waiting for me next morning, as eager to be on the trail as a dog in leash.

"We are going to call on Dr. Tresman, in Montagu Street," he said, stopping a taxi. "You will tell him that you have reason to believe that his house is being watched, and will be burgled on the first opportunity. If the opportunity is given, it may happen to-night, which will suit us admirably, because we have got to keep watch every night in his room until it is burgled. Of course, you will tell him who you are, and get his permission. We don't want to have to commit burglary ourselves in order to catch the thief."

"Why do you expect this particular doctor will be visited?" I asked.

"It is part of my theory," was all the explanation I could get out of him.