d out, and with very little delay Samuel was released. But
with the message from the police station, the fat was in the fire as
regarded Lady H----. Her husband necessarily became acquainted with
everything, and there was serious domestic trouble.

Samuel was glad enough to get quit of the business with no worse than a
bad fright, as may well be supposed. He showed himself most grateful to
Hewitt in after times, giving him excellent confidential advice and
information more than once in matters connected with the diamond trade.
He is still in business, I believe, in a much larger way, and I have no
doubt he is the wiser for his experience, and for the lesson which
Hewitt did not forget to rub well in: that it is useless and worse to
place a confidential matter in the hands of a man of Hewitt's
profession, and at the same time withhold particulars of the case,
however unessential they may appear to be.

* * * * *

But meantime, on the way to Vine Street I asked Hewitt what led him to
suppose that the new key on Denson's bunch fitted a lock in that
particular office building.

"Call it a lucky guess, if you like," Hewitt answered; "but as a matter
of fact it was prompted by pure common sense. Plummer showed me the
things found on the body, and I saw at once that the keys offered the
only chance of immediate information. I went through them one by one.
There was his latchkey--the key with which he had gone into his lodgings
to fetch away the disguise. There was another largish key, equally
old--probably the key of his office door. There were other smaller keys,
also old--plainly belonging to bags and trunks and drawers and so forth.
And then there was the large, perfectly new key. What was that? It was
not the key of any bag or drawer, clearly--it was the key of a door--a
door with a lever lock. What door? Had Denson some other office? Perhaps
he had, but first it was best to begin by trying it on places we were
already acquainted with. At once I thought of Denson's disappearance
unobserved by the housekeeper. Could this be the key of some private
exit from the office building? I resolved to test that conjecture first,
and it turned out to be the right one. Being successful so far, of
course I turned to the other new key and tried that, as you saw."

"But what of that triangular mark on the man's forehead?"

Martin Hewitt became deeply thoughtful. "That," he said, "is a matter
wholly bey