"Accordingly," Mostyn continued, "we have placed it in this room,
from which I fancy it would puzzle the most accomplished thief to
remove it."

The party, myself included, stared about the place, as he went on
to explain--

"We have four large windows here; as you see. The Burton Room
occupies the end of a wing; there is only one door; it communicates
with the next room, which in turn opens into the main building by
another door on the landing. We are on the first floor; these two
east windows afford a view of the lawn before the main entrance;
those two west ones face Orpington Square; all are heavily barred
as you see. During the day there is a man always on duty in these
two rooms. At night that communicating door is locked. Short of
erecting a ladder in full view either of the Square or of Great
Orchard Street, filing through four iron bars and breaking the
window and the case, I fail to see how anybody can get at the
slipper here."

"If a duplicate key to the safe--" another voice struck in; I knew
it afterward for that of Professor Rhys-Jenkyns.

"Impossible to procure one, Professor," cried Mostyn, his eyes
sparkling with an almost boyish interest. "Mr. Cavanagh here holds
the keys of the case, under the will of the late Professor Deeping.
They are of foreign workmanship and more than a little complicated."

The eyes of the savants were turned now in my direction.