“Here their suspicions were soon changed to certainty, for, on reaching the first-floor, they heard strange muffled groans proceeding from one of the rooms, the door of which was locked, though the key had not been removed.  They opened the door, and found the caretaker and his wife sitting on the floor, with their backs against the wall.  Both were bound hand and foot, and the head of each was enveloped in a green-baize bag; and when the bags were taken off, each was found to be lightly but effectively gagged.

“Each told the same story.  The caretaker, fancying he heard a noise, armed himself with a truncheon, and came downstairs to the first-floor, where he found the door of one of the rooms open, and a light burning inside.  He stepped on tiptoe to the open door, and was peering in, when he was seized from behind, half suffocated by a pad held over his mouth, pinioned, gagged, and blindfolded with the bag.

“His assailant—­whom he never saw—­was amazingly strong and skilful, and handled him with perfect ease, although he—­the caretaker—­is a powerful man, and a good boxer and wrestler.  The same thing happened to the wife, who had come down to look for her husband.  She walked into the same trap, and was gagged, pinioned, and blindfolded without ever having soon the robber.  So the only description that we have of this villain is that furnished by the constable.”

“And the caretaker had no chance of using his truncheon?” said Thorndyke.

“Well, he got in one backhanded blow over his right shoulder, which he thinks caught the burglar in the face; but the fellow caught him by the elbow, and gave his arm such a twist that he dropped the truncheon on the floor.”

“Is the robbery a very extensive one?”

“Ah!” exclaimed Mr. Loewe, “that is just what we cannot say.  But I fear it is.  It seems that my brother had quite recently drawn out of his bank four thousand pounds in notes and gold.  These little transactions are often carried out in cash rather than by cheque”—­here I caught a twinkle in Thorndyke’s eve—­“and the caretaker says that a few days ago Isaac brought home several parcels, which were put away temporarily in a strong cupboard.  He seemed to be very pleased with his new acquisitions, and gave the caretaker to understand that they were of extraordinary rarity and value.

“Now, this cupboard has been cleared out.  Not a vestige is left in it but the wrappings of the parcels, so, although nothing else has been touched, it is pretty clear that goods to the value of four thousand pounds have been taken; but when we consider what an excellent buyer my brother is, it becomes highly probable that the actual value of those things is two or three times that amount, or even more.  It is a dreadful, dreadful business, and Isaac will hold me responsible for it all.”

“Is there no further clue?” asked Thorndyke.  “What about the cab, for instance?”