till something was done
toward clearing the mystery up, and, although, as I have said, I don't
suspect either in the least, I acquiesced."

"Just so. Now--I am assuming that you wish me to undertake the recovery of
these drawings?"

The engineer nodded hastily.

"Very good; I will go round to your office. But first perhaps you can tell
me something about your assistants--something it might be awkward to tell
me in their presence, you know. Mr. Worsfold, for instance?"

"He is my draughtsman--a very excellent and intelligent man, a very smart
man, indeed, and, I feel sure, quite beyond suspicion. He has prepared
many important drawings for me (he has been with me nearly ten years now),
and I have always found him trustworthy. But, of course, the temptation in
this case would be enormous. Still, I can not suspect Worsfold. Indeed,
how can I suspect anybody in the circumstances?"

"The other, now?"

"His name's Ritter. He is merely a tracer, not a fully skilled
draughtsman. He is quite a decent young fellow, and I have had him two
years. I don't consider him particularly smart, or he would have learned a
little more of his business by this time. But I don't see the least reason
to suspect him. As I said before, I can't reasonably suspect anybody."

"Very well; we will get to Chancery Lane now, if you please, and you can
tell me more as we go."

"I have a cab waiting. What else can I tell you?"

"I understand the position to be succinctly this: The drawings were in the
office when you arrived. Nobody came out, and nobody went in; and _yet_
they vanished. Is that so?"

"That is so. When I say that absolutely nobody came in, of course I except
the postman. He brought a couple of letters during the morning. I mean
that absolutely nobody came past the barrier in the outer office--the
usual thing, you know, like a counter, with a frame of ground glass over
it."

"I quite understand that. But I think you said that the drawings were in a
drawer in your _own_ room--not the outer office, where the draughtsmen
are, I presume?"

"That is the case. It is an inner room, or, rather, a room parallel with
the other, and communicating with it; just as your own room is, which we
have just left."

"But, then, you say you never left your office, and yet the drawings
vanished--apparently by some unseen agency--while you were there in the
room?"

"Let me explain more clearly." The cab was bowling smoothly along the
Strand, an