“Well,” said Sowerby, turning over a page of his notebook, “it looks like a series of vaults, and the Rev. Mr. Firmingham, a local vicar whom I got to inspect it this morning, assures me, positively, that it's a crypt.”

“A crypt!” exclaimed Dunbar, fixing his eyes upon his subordinate.

“A crypt—exactly. A firm dealing in grease occupied the warehouse before Kan-Suh Concessions rented it, and they never seem to have suspected that the place possessed any cellars. The actual owner of the property, Sir James Crozel, an ex-Lord Mayor, who is also ground landlord of the big works on the other side of the lane, had no more idea than the man in the moon that there were any cellars beneath the place. You see the vaults are below the present level of the Thames at high tide; that's why nobody ever suspected their existence. Also, an examination of the bare walls—now stripped—shows that they were pretty well filled up to the top with ancient debris, to within a few years ago, at any rate.”

“You mean that our Chinese friends excavated them?”

“No doubt about it. They were every bit of twenty feet below the present street level, and, being right on the bank of the Thames, nobody would have thought of looking for them unless he knew they were there.”

“What do you mean exactly, Sowerby?” said Dunbar, taking out his fountain-pen and tapping his teeth with it.

“I mean,” said Sowerby, “that someone connected with the gang must have located the site of these vaults from some very old map or book.”

“I think you said that the Reverend Somebody-or-Other avers that they were a crypt?”

“He does; and when he pointed out to me the way the pillars were placed, as if to support the nave of a church, I felt disposed to agree with him. The place where the golden dragon used to stand (it isn't really gold, by the way!) would be under the central aisle, as it were; then there's a kind of side aisle on the right and left and a large space at top and bottom. The pillars are stone and of very early Norman pattern, and the last three or four steps leading down to the place appear to belong to the original structure. I tell you it's the crypt of some old forgotten Norman church or monastery chapel.”

“Most extraordinary!” muttered Dunbar.