as I had found, that the appointment was a hoax and
"the man with a box" a myth.

"You see," said Gatton, "the scheme of the plotter was simply this: to
get Coates out of the way for a long enough time to allow the
substitution of the telephone to be accomplished. The fact that Coates
had closed the windows before leaving the house didn't interfere very
much with the scheme. It's an old-fashioned catch on the ante-room
window, and I have seen the marks upon the brass-work where it was
forced from the outside with the blade of a knife. For the person who
opened the window to take out the real telephone and put the other in
its place was easy; and all that remained was to lift the gas-cylinder
on to the shed and partly reclose the window as we found it. Coates,
even if he had troubled to look, would not have noticed any difference
in the dusk. It is the next move, however, which _I_ find most
interesting."

Gatton spoke with repressed excitement, and:

"What do you mean by 'the next move'?" I asked.

"Well," he replied, "we have good evidence to show that the assassin
possesses an almost Napoleonic capacity for working by the time-table.
Witness the employment of Constable Bolton in the Red House
affair--which showed that our man was perfectly acquainted with the
movements of the officer on that beat and timed his scheme
accordingly. Very well ... having laid the telephone trap in your
ante-room--did our man hurry away and make the call _in person_,
which brought Coverly to the 'phone?--or did he remain watching the
house and give the signal to _some one else_ to do it?"

"I cannot imagine, Gatton. Nor does the point strike me as important."

"No?" said Gatton, smiling triumphantly. "Then I must explain.
Whereas, in the Red House, the scheme worked _automatically_--for the
time of Sir Marcus's arrival was _fixed_--in the present instance,
some one had to watch for _your_ return from the mythical
appointment!"

"For _my_ return?"

"Unquestionably! This scheme was arranged for your benefit, Mr.
Addison. Unknowingly, poor Coverly saved you from a dreadful fate at
the price of his own life! You see, they did not know that Coverly was
coming here! Now, it will not have escaped your attention that he wore
a soft felt hat, a light overcoat, and carried a black cane. So did
_you_ when you went out to keep the appointment made by the assassin!"

He paused, staring at me hard, and:

"Whoever was watching for your retu