When the messenger had been despatched, Naball drew his seat up to the table, and began to make some notes, after which he turned to Eugénie.

"I was firmly convinced of Stewart's guilt," he said quietly; "but what you have told me throws a new light on the subject. I said you could not do that--I beg your pardon--you can."

Eugénie bowed her head in acknowledgment of the apology, and asked him a question in a hesitating manner.

"You don't think Caprice is guilty?"

"I think nothing at present," he replied evasively; "not even that Stewart is innocent. When I see the boy, I'll tell you what I think."

They talked on together for a few minutes, and then there came a knock at the door. In reply to Ezra's permission to enter, the door opened, and Isaiah appeared on the threshold, holding some papers in his hand.

"Oh, you've come," said Ezra, as the boy shut the door after him.

"Yes; did you want me?" demanded Isaiah in a jerky manner, "'cos I never knowed you did."

"Didn't you meet a messenger?" asked Naball, turning his head round.

Isaiah deposited the papers he carried on Ezra's desk, and shook his head.

"No, I never met any one, I didn't," he answered. "Mr. Ezra asked me to bring all letters that came to the old 'un, so as these came, I did."

"That's right," said Lazarus, looking through the letters. "By-the-way, Isaiah, this gentleman wants to ask you a few questions."

"What, Mr. Naball?" said Isaiah in alarm. "Oh, sir, I never had nothing to do with it."

Naball smiled.

"No! no! that's all right," he said good-naturedly. "It would take a bigger man than a sprat like you to commit such a crime; but, tell me, do you know Caprice?"

Isaiah leered significantly.

"I've seen her on the stage, that's all."

"Never off?"

"Drivin' about the streets."

"Anywhere else?"

Isaiah glanced uneasily at Ezra, who laughed.

"Go on, Isaiah; it's all right."

"Well, I've seen her at the old 'un's place."

"Oh, indeed," said Naball quickly. "Often?"

"Yes--lots of times--at night--came to do business, I s'pose."

"When did you see her last?"

"Oh, not for a long time," replied Isaiah; "but do you remember the week them diamonds were stolen?"

"Yes, yes," said Naball eagerly.

Isaiah nodded.

"Well, she came to see the old 'un, then."

Naball suppressed his exultation with difficulty, and asked Isaiah another question.

"I say--those bank-notes that were stolen--"

"I never stole 'em."

"No one said you did," retorted Naball tartly; "but you wrote something on the back of one of 'em."

Isaiah turned scarlet, and shifted from one leg to the other.

"Well, you see," he murmured apologetically, "Mr. Stewart wanted to know a good 'un to back for the Cup, so I was afraid of the old 'un hearing, and as there wasn't no paper, I wrote on the back of one of 'em, 'Back Flat-Iron.'"

"In pencil?"

"No, in ink. Mr. Stewart, he laughs and nods, then puts the notes in the cash box, and puts 'em in the safe."

"That's all right," said Naball, dismissing him; "you can go."

Isaiah put on his hat, put his hands in his pockets, and departed, whistling a tune. When the door closed on him, Naball turned to his two companions with an exulting light in his eyes.

"What do you think now, Mr. Naball?" asked Eugénie.

"Think. I think as I've done all along," he replied. "Caprice stole those jewels herself, and sold them to old Lazarus."

"But what's that got to do with the death of my father?" asked Ezra.

"Perhaps nothing--perhaps a lot," said the detective. "I don't know but that boy's evidence has given me a clue. Suppose--I'm only supposing, mind you--Caprice stole her own diamonds, with Villiers as an accomplice. Suppose she took them to old Lazarus and sold 'em. Suppose Villiers, thinking the old man has them in his safe, goes to rob him, and commits the murder to do so. Suppose all that--I should think there would be a very pretty case against Villiers."

"Yes; but Keith's knife?" said Eugénie.

"Ah, now you have me," answered Naball, puzzled. "I don't know, unless Villiers managed to get it while Stewart was fighting with him on that night, and covered it in blood in order to throw suspicion on him."

"All your ideas are theoretical," said Ezra drily. "Perhaps Caprice never stole her own jewels, or sold them to my father."

"Yes, she did, I'll swear," retorted Naball decisively. "Why wouldn't she prosecute? why did I find Villiers with one of the jewels? You bet, she stole them for some freak, and I daresay Villiers committed the murder to get them back."

"I don't think my father would have kept such valuable jewels as that about the premises."

"No; he'd put 'em in the bank."

"No, he wouldn't," retorted Ezra; "he sent all his jewels to Amsterdam. And here," holding up a letter, "is an envelope with the Dut............