It was plain, by this time, that Mr. Bruff and I had made another mistake. The sailor with the black beard was clearly not a spy in the service of the Indian conspiracy. Was he, by any possibility, the man who had got the Diamond?

"After a little," pursued the Sergeant, "the cab moved on slowly down the street. The mechanic crossed the road, and went into the eating-house. The boy waited outside till he was hungry and tired - and then went into the eating-house, in his turn. He had a shilling in his pocket; and he dined sumptuously, he tells me, on a black-pudding, an eel-pie, and a bottle of ginger-beer. What can a boy not digest? The substance in question has never been found yet."

"What did he see in the eating-house?" I asked.

"Well, Mr. Blake, he saw the sailor reading the newspaper at one table, and the mechanic reading the newspaper at another. It was dusk before the sailor got up, and left the place. He looked about him suspiciously when he got out into the street. The boy - BEING a boy - passed unnoticed. The mechanic had not come out yet. The sailor walked on, looking about him, and apparently not very certain of where he was going next. The mechanic appeared once more, on the opposite side of the road. The sailor went on, till he got to Shore Lane, leading into Lower Thames Street. There he stopped before a public-house, under the sign of 'The Wheel of Fortune,' and, after examining the place outside, went in. Gooseberry went in too. There were a great many people, mostly of the decent sort, at the bar. 'The Wheel of Fortune' is a very respectable house, Mr. Blake; famous for its porter and pork-pies."

The Sergeant's digressions irritated me. He saw it; and confined himself more strictly to Gooseberry's evidence when he went on.

"The sailor," he resumed, "asked if he could have a bed. The landlord said 'No; they were full.' The barmaid corrected him, and said 'Number Ten was empty.' A waiter was sent for to show the sailor to Number Ten. Just before that, Gooseberry had noticed the mechanic among the people at the bar. Before the waiter had answered the call, the mechanic had vanished. The sailor was taken off to his room. Not knowing what to do next, Gooseberry had the wisdom to wait and see if anything happened. Something did happen. The landlord was called for. Angry voices were heard up-stairs. The mechanic suddenly made his appearance again, collared by the landlord, and exhibiting, to Gooseberry's great surprise, all the signs and tokens of being drunk. The landlord thrust him out at the door, and threatened him with the police if he came back. From the altercation between them, while this was going on, it appeared that the man had been discovered in Number Ten, and had declared with drunken obstinacy that he had taken the room. Gooseberry was so struck by this sudden intoxication of a previously sober person, that he couldn't resist running out after the mechanic into the street. As long as he was in sight of the public-house, the man reeled about in the most disgraceful manner. The moment he turned the corner of the street, he recovered his balance instantly, and became as sober a member of society as you could wish to see. Gooseberry went back to 'The Wheel of Fortune' in a very bewildered state of mind. He waited about again, on the chance of something happening. Nothing happened; and nothing more was to be heard, or seen, of the sailor. Gooseberry decided on going back to the office. Just as he came to this conclusion, who should appear, on the opposite side of the street as usual, but the mechanic again! He looked up at one particular window at the top of the public-house, which was the only one that had a light in it. The light seemed to relieve his mind. He left the place directly. The boy made his way back to Gray's Inn - got your card and message - called - and failed to find you. There you have the state of the case, Mr. Blake, as it stands at the present time."

"What is your own opinion of the case, Sergeant?"

"I think it's serious, sir. Judging by what the boy saw, the Indians are in it, to begin with."

"Yes. And the sailor is evidently the person to whom Mr. Luker passed the Diamond. It seems odd that Mr. Bruff, and I, and the man in Mr. Bruff's employment, should all have been mistaken about who the person was."

"Not at all, Mr. Blake. Considering the risk that person ran, it's likely enough that Mr. Luker purposely misled you, by previous arrangement between them."

"Do you understand the proceedings at the public-house?" I asked. "The man dressed like a mechanic was acting of course in the employment of the Indians. But I am as much puzzled to account for his sudden assumption of drunkenness as Gooseberry himself."

"I think I can give a guess at what it means, sir," said the Sergeant. "If you will reflect, you will see that the man must have had some pretty strict instructions from the Indians. They were far too noticeable themselves to risk being seen at the bank, or in the public-house - they were obliged to trust everything to their deputy. Very good. Their deputy hears a certain number named in the public-house, as the number of the room which the sailor is to have for the night - that being also the room (unless our notion is all wrong) which the Diamond is to have for the night, too. Under those circumstances, the Indians, you may rely on it, would insist on having a description of the room - of its position in the house, of its capability of being approached from the outside, and so on. What was the man to do, with such orders as these? Just what he did! He ran up-stairs to get a look at the room, before the sailor was taken into it. He was found there, making his observations - and he shammed drunk, as the easiest way of getting out of the difficulty. That's how I read the riddle. After he was turned out of the public-house, he probably went with his report to the place where his employers were waiting for him. And his employers, no doubt, sent him back to make sure that the sailor was really settled at the public-house till the next morning. As for what happened at 'The Wheel of Fortune,' after the boy left - we ought to have discovered that last night. It's eleven in the morning, now. We must hope for the best, and find out what we can."