"Let me clear up the banker first," said Quarles. "To-day, Wigan, he gave himself away when he said he would know if Lady Leconbridge were wearing paste. Of course he would know, because he had the real stones. No doubt he would have pronounced them paste before the assembled guests—a disclosure which might have proved disastrous to Lady Leconbridge. Whether Hartmann knows the true story of the necklace or not, I cannot say."

"What is the true story?" asked Zena.

"We may conjecture fairly confidently up to a certain point," said the professor. "As Wigan told us the other day, Mr. Dinneford objected to his daughter's engagement to Rupert Lester. Dinneford is a wealthy man, fond of his money; Lester was a spendthrift, and in debt. Lord Leconbridge came to the rescue and paid his debts, after a severe interview with his son, no doubt. I will hazard a guess that the son did not tell his father everything—sons, in these circumstances, seldom do. The creditor left unpaid, some hireling of Hartmann's it may be, began to press the young man—may have suggested, even, how easily he could raise money on the diamonds, which were so seldom worn."

"Do you mean that Lady Leconbridge helped him?" asked Zena.

"It may be," said Quarles. "Knowing how enraged her husband would be with his son, she may have lent Lester the diamonds to pawn. The fact that she appealed to him to support her in her choice of the pearls lends weight to this view, but the housemaid's story of hearing an angry woman's voice in the corridor leads me to think otherwise. I fancy Lester must have heard his father speak to Hartmann at the reception, and gathered that the diamonds were to be a proof of something to the banker. Knowing Hartmann's knowledge of stones, he went to Lady Leconbridge, took her into the corridor, where she learnt for the first time that he had taken the real jewels, and that she was wearing the imitation he had put in their place. She was angry, refused to have anything to do with the deception, and then, partly to help him, but chiefly to thwart her enemy, Hartmann, she consented to lose the diamonds. Lester took the necklace, and, to give the idea that a robbery had taken place, and the thief escaped, broke the window of the small room. When he saw the advertisement he returned the necklace, hoping the mystery would come to an end so far as the outer world was concerned; and at the present time, I imagine, he is either trying to raise money enough to redeem the jewels, or is getting up his courage to confess to his father. He has probably promised Lady Leconbridge that he will do one or the other before she returns from Grasslands."

What Rupert Lester's confession meant to his father no one will ever know probably. Practically, in every detail, he confirmed the professor's theory, and possibly Quarles and I saw Lord Leconbridge nearer the breaking point than anyone else.

Leconbridge showed us Hartmann's letter of apology.

"The snake's fangs are drawn," said Quarles. "Now you can let it be known through the press that the necklace lost at the Duchess of Exmoor's has been returned. It is the exact truth. The real diamonds you may redeem as soon as you like, and I think this letter insures that no lies will be told about your wife in future."

"But my son is——"

"He is your son, Lord Leconbridge, and our word is pledged not to make the person who returned the necklace suffer."