"Three hundred years."

"They are not often worn, I believe?"

"Not often."

"And on this particular night you expressed a wish that they should be worn?"

"I did."

"Quite natural at such an important reception," said Quarles, as though the idea of there being a definite purpose behind the wish had never entered his head. "Lady Leconbridge offered no objection, I presume?"

"She preferred the pearls, but she changed them at my request."

"You were not in the habit of keeping the jewels at your banker's?"

"No; they were kept in a safe in my wife's room."

"Rather risky," said Quarles. "To an outsider it seems foolish to keep such jewels constantly in the house, especially when they are so seldom worn. Have you ever contemplated selling the diamonds?"

"Never."

"Has Lady Leconbridge at any time suggested that you should?"

"Certainly not!"

"You are prepared to swear that your wife wore this necklace at the d.u.c.h.ess of Exmoor's reception?" said Quarles, holding up the jewels.

"I am."

"It only shows how risky it is to keep such valuables in the house.

These stones are not diamonds, but paste."

"What!"

Well might Lord Leconbridge start forward and look at the necklace. I did the same myself.

"Very well executed, but paste," said Quarles.

"Do you suggest----"

"Pardon me, I have made no suggestion; I have merely stated a fact."

"It isn't true; it's absurd!"

"You may prove me right or wrong by showing the stones to an expert.

Why not show them to Jacob Hartmann?"

"Hartmann! Why to him?"

"Because I believe he knows more about precious stones than any man in this country."

For the s.p.a.ce of a minute Leconbridge and the professor stood looking at each other in silence.

"I did not know that," said Leconbridge.

"I am a man of the world rather than a detective," said Quarles, his manner suddenly changing, "and to some extent I can appreciate your position. May I become a friendly adviser? Lock this necklace up, and let no one know it has been returned. Take my word for it that the stones are imitation, and leave the matter in my hands. I give you my word that I believe, when the full explanation is forthcoming, you will be perfectly satisfied with it. Will you trust me, Lord Leconbridge?"

"Yes," came the firm answer, after a pause.

"It will be the work of a few hours, I hope," said Quarles, taking up his hat; "and, of course, it is agreed that the person who returned the jewels is not to suffer."

Quarles was thoughtful as we walked away from Hill Street, and well he might be. He had promised a great deal, and how he was going to fulfil that promise was beyond my comprehension.

"You expected to surprise Lord Leconbridge into an admission and were disappointed?" I said.

"On the contrary, he told me rather more than I expected," was the answer. "Evidently he had a purpose in wanting his wife to wear the diamonds. It is fairly clear, I think, that he did not believe she had parted with the necklace, therefore his purpose had to do with some one who would be at the reception that night. Jacob Hartmann seems to fit that part. It is wonderful, Wigan, what a lot of trouble is caused when a person tells only half the truth."

"I can understand Lord Leconbridge's reticence," I said.

"Yes. As a fact, I wasn't thinking of Lord Leconbridge just at the moment. My present difficulty is to decide which road to take. One is easy, the other difficult. Let us get into this taxi. How true it is that the longest way round is often the shortest road home."

He told the man to drive to Old Broad Street.

"A theory may lead to disaster, professor," I said.

"Ah! but we are going into the city to look for facts. I have noticed, Wigan, that lately you have become strangely susceptible to beauty."

I wondered if he had guessed that I was in love with Zena.

"If you refer to Lady Leconbridge----"

"I don't. I speak in the abstract. Still, there exists a certain amount of evidence against her, and your refusal to admit it has warped your judgment in this case, I fancy. Do you know Jacob Hartmann?"

"No."

"A very pleasant man, I am told. We are going to see him, so shall be able to judge for ourselves. You must question; I am merely your a.s.sistant. Your line is this: You have got Lord and Lady Leconbridge's story, and you are not quite satisfied. You recognize that the affair is a delicate one, but you are not going to wink at the compounding of a felony to hush up a family scandal."

All the way to the city Quarles continued to coach me, giving me certain points and questions which I was to lead up to gradually. I understood why he had warned me against susceptibility to beauty, for the whole trend of these questions was toward d.a.m.ning Lady Leconbridge.

Mr. Hartmann received us in his private room, and, although reluctant to talk about an affair which was no business of his, was willing to give any help in his power. I repeated the story as Lord Leconbridge had first told it to me, just the bare facts, and I dwelt upon the delicacy of the affair.

"You did not actually see the necklace, I suppose?"

"No; and in the excitement I was not presented to Lady Leconbridge,"

Hartmann answered.

"Was she very much agitated?" I asked.