swarthy complexion he could never have passed himself

off as the fair stocky doctor. It is child's play, of course, to put on an additional inch or so for the part of James, or the Professor. In the same way he must have a short

straight nose. Additions can be built on to a nose by

skilful make up, but a large nose cannot be successfully reduced at a moment's notice. Then again, he must be a

fairly young man, certainly not over thirty-five. You

see, we are getting somewhere. A man between thirty

and thirty-five, of medium height and colouring, an

adept in the art of make up, and with very few or any

teeth of his own."

"What?"

"Surely, Hastings. As the keeper, his teeth were

broken and discoloured, in Paris they were even and

white, as the doctor they protruded slightly, and as

Savaronoff they had unusually long canines. Nothing

alters the face so completely as a different set of teeth. You see where all this is leading us?"

"Not exactly," I said cautiously.

"A man carries his profession written in his face, they say."

"He's a criminal," I cried.

"He is an adept in the art of making up."

"It's the same thing."

"Rather a sweeping statement, Hastings, and one

which would hardly be appreciated by the theatrical

world. Do you not see that the man is, or has been, at

one time or another, an actor?"

"An actor?"

"But certainly. He has the whole technique at his

finger-tips. Now there are two classes of actors, the one who sinks himself in his part, and the one who manages

to impress his personality upon it. It is from the latter class that actor managers usually spring. They seize a

part and mould it to their own personality. The former

class is quite likely to spend its days doing Mr. Lloyd

George at different music halls, or impersonating old

men with beards in repertory plays. It is among that

former class that we must look for our Number Four.

He is a supreme artist in the way he sinks himself in each part he plays."

I was growing interested.

"So you fancy you may be able to trace his identity through his connection with the stage?"

"Your reasoning is always brilliant, Hastings."

"It might have been better," I said coldly, "if the idea had come to you sooner. We have wasted a lot of

time."

"You are in error, mon ami. No more time has been

wasted than was unavoidable. For some months now

my agents have been engaged on the task. Joseph

Aarons is one of them. You remember him? They have

compiled a list for me of men fulfilling the necessary

qualifications--young men round about the age of

thirty, of more or less nondescript appearance, and with a gift for playing character parts--men, moreover, who

have definitely left the stage within the last three years."

"Well?" I said, deeply interested.

"The list was, necessarily, rather a long one. For