to come to me in
the event of his having received a mysterious summons. It worked, as
you know, and Doctor Alwyn responded."

"Well, if you hadn't been able to read the cryptogram, sir, the Lord
knows what would have happened!"

"And if you hadn't trodden on the cat's tail--" Blaine suggested
dryly.

[Illustration: An image of a coded message is shown here in the text.]

Guy glanced at him in sudden, swift comprehension.

"Why, look here, sir, I believe you knew that Emily and her father
were the two mysterious boarders at Mrs. Quinlan's, all the time! You
said it was significant that you hadn't been able to trace the number
of the taxicab in which they had run away from the neighborhood! There
never was a taxicab in all Illington which couldn't be traced by its
number! You knew, of course, that that story of Mrs. Quinlan's was a
fake, and then when I told you of the two concealed people there, you
had it all doped out! Oh, why didn't you tell me?"

"Because I didn't want you to precipitate matters just then, Guy," the
detective responded, kindly. "The house was watched--they couldn't get
away."

"That's a good one!" Young Morrow looked his self-disgust. "Hire
operatives on your staff, sir, and then have to set others to tail
them, and see that they don't get into trouble! Heavens, what an idiot
I am! I've found out one thing, though, from those cryptograms"--he
pointed to the cipher notes on the desk. "Music's a cinch! I can read
it already, and I'm going to start in and learn how to play on
something or other, the first chance I get! There's a fellow next door
to Mrs. Quinlan's with a clarinet--" He paused, and his face sobered
as he added: "But I forgot! I sha'n't be there any more."

Before Blaine could speak, there was a knock upon the door, and Marsh
entered with hurried circumspection. There was a look of latent,
shocked importance upon his usually impassive face, and he carried in
his hand a newspaper which was still damp from the press.

"I beg your pardon, sir, but I thought you would want to know at once.
There's been a murder! Paddington, the private detective, was found in
the Rhododendron Alley, just off the Mall in the park, stabbed to the
heart!"

Henry Blaine took the paper and spread it out upon the desk before
him, as Guy Morrow, with a soft, low whistle, turned away. The "extra"
imparted little more than the secretary's announcement had done. There
was no known motive for the crime, no