"Is Fullaway!" suddenly exclaimed Allerdyke, thrown off his guard and
speaking aloud. "And, by Gad!--he's got that man Chilverton with him.
This--by the Lord Harry, he's caught sight of us, too!"

Fullaway was coming quickly up the lawn from the direction of the
Serpentine; he looked unusually alert, vigorous, and bustling; by his
side, hurrying to keep pace with him, was the New York detective. And
Fullaway's keen eyes, roving about, fell on Allerdyke and the chief
and he made through the crowd in their direction, beckoning Chilverton
to follow.

"Hullo--hullo!" he exclaimed, clapping a hand on Allerdyke's shoulder,
nodding to the chief, and staring inquisitively at Appleyard. "So you're
here, too, eh, Allerdyke? It wasn't you who sent me that mysterious
message, was it?"

"What message?" growled Allerdyke. "Be careful! Don't attract
attention--there are things going on here, I promise you! Drop into
that chair, man--tell Chilverton to sit down. What message are you
talking about?"

Fullaway, quick to grasp the situation, sat down in a chair which
Appleyard pulled forward and motioned his companion to follow his
example.

"I got a queer message--typewritten--on a sheet of notepaper which bore
no address, about an hour ago," he said. "It told me that if I came here,
to this Hyde Park tea-house, at two o'clock, I'd have this confounded
mystery explained. No signature--nothing to show who or where it came
from. So I set out. And just as I was stepping into a taxi to come on
here, I met Chilverton, so he came along with me. What brings you, then?
Similar message, eh? And what--"

"Hush!" whispered Appleyard. "Miss Slade's coming out of the tea-house!
And who's the man that's with her?"

All five men glanced covertly over their shoulders at the open door of
the tea-house, some twenty to thirty yards away. Down its steps came Miss
Slade, accompanied by a man whom none of them had ever seen before--a
well-built, light-complexioned, fair-haired man, certainly not an
Englishman, but very evidently of Teutonic extraction, who was talking
volubly to his companion and making free use of his hands to point or
illustrate his conversation. And when he saw this man, the chief turned
quickly to Allerdyke and intercepted a look which Allerdyke was about to
give him--the same thought occurred to both. Here was the man described
by the hotel-keeper of Eastbourne Terrace and the shabby establishment
away in the Docks!

"Miss S