cannot say, when suddenly it began to rain in torrents.

What I might have done or what I had hoped to do is of no importance;
for as I sat there staring out at the dismal rain-swept street, a man
came along, saw the head-lamps of the cab and stopped, peering in my
direction. Evidently perceiving that I drove a cab and not a private
car, he came towards me.

"Are you disengaged?" he asked.

Whether it was that I sympathized with him--he had no topcoat or
umbrella--or whether I was guided by Fate I know not, but as he spoke
I determined to give up my dreary vigil for that night. _Pardieu!_ but
certainly it was Fate again!

"Well, I suppose I am, sir," I said, and asked him where he wanted
to go.

He gave an address not five hundred yards from my own rooms! I thought
this so curious that I hesitated no longer.

"Jump in," I said; and still seeking in my mind for a link between the
scorpion case and China, I drove off, and in less than half an hour,
for the streets were nearly empty, arrived at my destination.

The passenger, whose name was Dr. Keppel Stuart, very kindly suggested
a glass of hot grog, and I did not refuse his proferred hospitality.
When I came out of his house again, the rain had almost ceased, and
just as I stooped to crank the car I thought I saw a shadowy figure
moving near the end of a lane which led to the tradesmen's entrance of
Dr. Stuart's house. A sudden suspicion laid hold upon me--a horrible
doubt.

Having driven some twenty yards along the road, I leaned from my seat
and looked back. A big man wearing a black waterproof overall was
standing looking after me!

Remembering how cleverly I had been trailed from Miguel's cafe to my
flat, in Paris (for I no longer doubted that someone had followed me
on that occasion), I now perceived that I might again be the object of
the same expert's attention. Stopping my engine half-way along the
next road, I jumped out and ran back, hiding in the bushes which grew
beside the gate of a large empty house. I had only a few seconds to
wait.

A big closed car, running almost silently, passed before me ... and
"Le Balafre" was leaning out of the window!

At last I saw my chance of finding the headquarters of "The Scorpion."
Alas! The man of the scar was as swift to recognize that possibility
as I. A moment after he had passed my stationary cab, and found it to
be deserted, his big car was off like the wind, and even before I
could step out from the