t he had the missing pigtail in his pocket," he said, "is
proof enough to my mind that he did the murder."

"And to mine."

"There's another point," he added, "which throws a lot of light on the
matter. You and Mr. Harley were out of town at the time of the Huang
Chow case; but the Chief and I outlined it, you remember, one night in
Mr. Harley's rooms?"

"I remember it perfectly; the giant spider in the coffin------"

"Yes; and a certain Ah Fu, confidential servant of the old man, who used
to buy the birds the thing fed on. Well, Mr. Knox, Huang Chow was the
biggest dealer in illicit stuff in all the East End--and this battered
thing at our feet is--Ah Fu!"

"Huang Chow's servant?"

"Exactly!"

I stared, uncomprehendingly, and:

"In what way does this throw light on the matter?" I asked.

Durham--a very intelligent young officer--smiled significantly.

"I begin to see light!" he declared. "The gentleman who made off just as
I arrived on the scene probably had a private quarrel with the Chinaman
and was otherwise not concerned in any way."

"I am disposed to agree with you," I said guardedly.

"Of course, you've no idea of his identity?"

"I'm afraid not."

"We may find him," mused the officer, glancing at me shrewdly, "by
applying at the offices of the Planet Line, but I rather doubt it. Also
I rather doubt if we'll look very far. He's saved us a lot of trouble,
but"--peering about in the shadowy corners which abounded--"didn't I see
somebody else lurking around here?"

"I'm almost certain there was someone else!" I cried. "In fact, I could
all but swear to it."

"H'm!" said the detective. "He's not here now. Might I trouble you to
walk along to Limehouse Police Station for the ambulance? I'd better
stay here."

I agreed at once, and started off.

Thus a second time my plans were interrupted, for my expedition that
night ultimately led me to Bow Street, whence, after certain formalities
had been observed, I departed for my chambers, the mysterious pigtail
in my pocket. Failing the presence of Durham, the pigtail must have been
retained as evidence, but:

"We shall know where to find it if it's wanted, Mr. Knox," said the Yard
man, "and I can trust you to look after your own property."

The clock of St. Paul's was chiming the hour of two when I locked the
door of my chambers and prepared to turn in. The clangour of the final
strokes yet vibrated through the night's silence when someone set my ow