of early Victorian fashion and massive folding shutters
were provided to close the French windows. He never used them, as a
matter of fact, but now he tested the fastenings which kept them in
place against the inner wall and even moved them in order to learn if
they were still serviceable.

Of all the mysteries which baffled him, that of the piece of
cardboard in the envelope sealed with a Chinese coin was the most
irritating. It seemed like the purposeless trick of a child, yet it
had led to the presence of the cowled man--and to the presence of
Mlle. Dorian. Why?

He sat down at his table again.

"Damn the whole business!" he said. "It is sending me crazy."

Selecting from the heap of documents a large sheet of note-paper
bearing a blue diagram of a human bust, marked with figures and
marginal notes, he began to read the report to which it was
appended--that of Dr. Halesowen. It stated that the late Sir Frank
Narcombe had a "horizontal" heart, slightly misplaced and dilatated,
with other details which really threw no light whatever upon the
cause of his death.

"_I_ have a horizontal heart," growled Stuart--"and considering my
consumption of tobacco it is certainly dilatated. But I don't expect
to drop dead in a theatre nevertheless."

He read on, striving to escape from that shadowy apprehension, but as
he read he was listening to the night sounds of London, to the
whirring of distant motors, the whistling of engines upon the railway
and dim hooting of sirens from the Thames. A slight breeze had arisen
and it rustled in the feathery foliage of the acacias and made a
whispering sound as it stirred the leaves of the privet hedge.

The drone of an approaching car reached his ears. Pencil in hand, he
sat listening. The sound grew louder, then ceased. Either the car
had passed or had stopped somewhere near the house. Came a rap on
the door.

"Yes," called Stuart and stood up, conscious of excitement.

Mrs. M'Gregor came in.

"There is nothing further you'll be wanting to-night?" she asked.

"No," said Stuart, strangely disappointed, but smiling at the old
lady cheerfully. "I shall turn in very shortly."

"A keen east wind has arisen," she continued, severely eyeing the
opened windows, "and even for a medical man you are strangely
imprudent. Shall I shut the windows?"

"No, don't trouble, Mrs. M'Gregor. The room gets very stuffy with
tobacco smoke, and really it is quite a warm night. I shall close
them b