"You said you had something altogether different in view before we met.
What was it?"

"I'll tell you--let me see--I'll tell you on Thursday."

"Why not now?"

"Because it is the hardest thing in the world for a woman to be
single-minded, in the limited sense of concentration, I mean. Focus your
wits on Siddle to-day. I don't suggest any plan. I leave that to your own
intelligence. Vex him, and let him talk."

"Vex him!"

"Yes. What man won't get mad if he notices that his best girl is thinking
about a rival."

This time Doris did not blush. She was troubled and serious, very
serious.

"I'll do what I can," she promised. "When shall I see you again?"

"Soon. There's no hurry. All this is preparatory for Wednesday."

"Am I to tell my father nothing?"

"Please yourself. Not at present. I recommend you."

The car had stopped. It sped on when Doris alighted. She would be home
with her cakes at three o'clock, and Mr. Martin would never have noticed
her absence.

"A fine bit of work, if I may say so," exclaimed Fowler appreciatively.
"But I am jiggered if I can imagine what you're driving at."

Winter was cutting the end off a big cigar. He finished the operation to
his liking before answering earnestly:

"We stand or fall by the result of that girl's efforts. Furneaux
thinks so, and I agree with him absolutely. After five days, where are
we, Mr. Fowler? In the dark, plus a brigand's hat and hair. But there's
a queer belief in some parts of England that a phosphorescent gleam
shows at night over a deep pool in which a dead body lies. That's just
how I feel about Siddle. The man's an enigma. What sort of place is
Steynholme for a chemist of his capacities? Dr. Foxton has the highest
regard for him professionally, and I'm told he doctors people for miles
around. Yet he lives the life of a recluse. An old woman comes by day
to prepare his meals, and tidy the house and shop. His sole relaxation
is an hour of an evening in the village inn, his visits there being
uninterrupted since the murder. He was there on the night of the
murder, too. For the rest, he is alone, shut off from the world.
Without knowing it, he's going to fall into deep waters to-day, and
he'll emit sparks, or I'm a Chinaman.... I'll leave you here. Good-by!
See you on Tuesday, after lunch."

The superintendent drove on alone. He pondered the Steynholme affair in
all its bearings, but mostly did he weigh up Winter and Furneaux. At
last, he sig