And then the professor thanked the clerk, and we left the bank.

"We've got to find Frederick Ewing," said Quarles decidedly. "He is the keystone to the mystery. Without definite knowledge concerning him we are powerless, I fancy. Even if we make an arrest, even if we arrest a gang of men, we could prove nothing. They are not likely to be found carrying any of the missing jewels, and there is precious little evidence to be got out of a sovereign. Months must elapse before the jewels, one or two at a time, filter into the market, and no banknotes or bonds which might further us with a clew have been taken. Ewing must be found."

In this direction I was up against a blank wall. I gave instruction for every shop, every public-house in the neighborhood of Ewing's lodgings, to be visited, and practically there was no result. A tobacconist fancied he recognized a customer from the description given of him, but that was all. Ewing had once belonged to a rowing club at Hammersmith, but had gone in for little serious practice. And the day after Quarles and I had visited the bank I drew another blank. Bowman, the mortgage broker, returned to his office. Not only was it quite certain that none of the gold was hidden there, but he explained his absence so thoroughly that it was impossible to suppose he had anything to do with the affair.

Two or three days slipped by, days of strenuous work, which seemed absolutely useless, and then I got a wire from Quarles asking me to meet him at Chiswick Station that evening, which I did.

"I must apologize, Wigan," was his greeting. "It's my temperament, I suppose, but I cannot help keeping a line of argument to myself until I find that it really leads somewhere. This was my theory with regard to Ewing. Since he did not make friends, either in the bank or out of it, he was likely to be something of a dreamer. Such men usually are, unless they have some definite hobby to employ them. We heard of no such hobby in Ewing's case, and the fact that his rise in the bank had been rapid suggested a competent and conscientious worker. But he was a dreamer, all the same—a man looking forward to the future, and a man who dreams in this way usually looks forward to some definite point. In the case of a young man—and Ewing is not old—that point may be a woman. So I examined Ewing's desk. He was given to scribbling on it and smearing out the writing. There were a quantity of ink smudges, but some pen marks remained, figures for the most part, and I found a name—Ursula. That rejoiced me; it might have been Mary, and for one Ursula there are—well, a great many Marys in the world. I looked for a second name, dreading to find Smith. I found Ursula Ewing, that was his dream, Wigan; but I also found Ursula Yerbury. If he were in love with Ursula Yerbury, which seemed probable, and she with him, which of course was not certain, then I argued that she must live in easy distance from Hammersmith. If not, he would have constantly received letters from her, and we know that he received very few letters. Also, if they were in love, he might have deceived her regarding his dismissal, or she would keep his secret and shield him. Inquiry for her must therefore be made carefully, and I set Zena to work—a girl looking for a girl friend she had lost sight of. It proved easier than it might have been. We found there was a man named Yerbury living in Fulham; he was the third of the name Zena had tried, and he had a niece, Ursula, living in lodgings here in Chiswick. She is a typist, and should be home by this time in the evening. She is expecting an old school friend—that was the vague message Zena left with her landlady—she will see us."

"I congratulate you, professor; it looks as if you had got on Ewing's track."

"We shall know better in an hour's time," he answered. "No. 10 Old Cedar Lane is the address. Pleasant flavor in some of these Chiswick names."

There was nothing particularly striking about Ursula Yerbury, but her personality grew upon one. The moment we entered her small but comfortable sitting-room it was apparent to me that she was on her guard. She had expected some old school friend, and had been tricked. Quarles came to the point at once. To clear up the mystery of the sensational robbery in the city, he wanted to find Frederick Ewing. Miss Yerbury knew him, of course, and could no doubt supply the information.

"You have had your journey in vain," she answered.

"That is a pity," Quarles said, and in short, terse sentences he told her the history of the robbery, so far as we knew it, speaking of Ewing's dishonesty in a cold, matter-of-fact way, and giving reasons why Ewing should be suspected of helping a gang.