indeed; I think he's a frightfully clever physician and
scientist."

"But as a man?"

"I don't believe he is a man, quite," she laughed. "At least, one
can't exactly think of him as one."

"That's how he strikes me. Yet I suppose no one can be as phlegmatic
as he seems; there must be a spark of enthusiasm in him somewhere."

"Oh, but there is! Don't you know? He absolutely lives for research;
it's the one thing he takes an interest in. He practises medicine to
make a living, but he devotes every spare minute to hunting for
anti-toxins."

"Does he indeed? I know my aunt thinks very highly of him, but I'm
glad you do, too. Your opinion is worth something."

The time passed with amazing quickness, as they discovered when they
consulted their watches.

"Must you go back at once?" Roger asked as he tentatively reversed the
car and slowly headed for home.

"I don't want to be late," she said with a sigh. "It's my first case
here; I must be on my best behaviour! But--I've just thought of
something. Would it be very far out of our way if we went to the
doctor's villa in the Route de Grasse? I left my French lesson-books
there, and I'd like to fetch them."

"We can do it easily; only show me the house."

Before long they came in sight of the villa, which looked as tidy, as
smug and non-committal as it had done when she first approached it some
weeks ago. Alighting quickly from the car, Esther rang the bell and
waited, expecting momentarily to see the friendly Jacques answer the
summons. There was, however, no response.

"Is anyone staying here?" asked Roger.

"Yes, the doctor's servant, but he may have gone out."

She rang again; from the distant kitchen they could hear the faint
persistent peal.

"The place looks deserted for the moment, at any rate," Roger remarked,
gazing up at the closed windows.

With a sudden wry smile, Esther fished in her bag and produced a
latch-key.

"Isn't it stupid of me? I'd forgotten I still had it. I've meant
daily to give it back to the doctor, but I never think of it at the
right moment."

She fitted the key into the Yale lock, and in another moment the two
were standing inside the dim and chilly hall, looking about them. A
few circulars lay in a heap on the floor, there was a film of dust on
the polished parquet. A man's overcoat and hat adorned the rack. From
the salon a clock ticked loudly.

"Gloomy place, this," commented Roger, glancing into the c