us
criminal of unusual mould, remorseless as a tiger, with a neurasthenic
mind swayed by the unbridled savagery of natural impulse.

As Colwyn meditated over the murder, his original impression of the
guests assembled in the dining-room downstairs in a premeditated scene
set for its production came back to him with renewed force. The murderer
had taken his part in that scene as one of the unconscious audience,
dining and taking his share in the conversation, while his secret
consciousness was strained to an intense anticipation of the false
signal from his mechanical accomplice upstairs. Colwyn could picture him
joining in the mockery of meaningless phrases with dry lips, his ears
listening for every sound, his eyes covertly watching the crawling hands
of the clock. Then, when the crack had pealed forth, he had been able to
exchange suspense for action, and rush upstairs with the others,
confident in the feeling that, let suspicion point where it would, it
could not fall on him.

But the murderer had not foreseen the scream which preceded the shot.
How had he comported himself under the shock of that cry, which was
outside the region of his calculations? He had not time to reflect upon
its origin, to investigate its source. He had to steel his nerves to
face it because he dared not do otherwise. But its sudden effect on the
nerve centres of his brain, previously strained almost to the breaking
point, must have brought him to the verge of a subsequent collapse.

Colwyn believed he saw the end in sight. The presumptions, the facts,
and the motive all pointed to one figure as the murderer of Violet
Heredith. She had been killed from the dual motive of punishment in her
own case and vengeance on a greater offender than herself. The alibi had
been devised to ensure a tremendous revenge on the man by bringing him
to the gallows as her supposed murderer. That part of the plan had gone
astray, so the murderer, in the fanatical resolve of his latent fixed
idea, had recourse to a further expedient as daring and original as the
scheme which failed. The second instrument had been the means of his own
undoing.

But as he reached this final stage of his reasoning, Colwyn stopped
short in something like dismay. He had left a point of vital importance
out of his calculations. If the murderer was the man he thought, he was
downstairs in the dining-room at the time the false shot was fired. Then
whose hand had clutched Hazel Rath's t