"And the voice on the telephone?"

Again I saw that odd expression creep over Gatton's face, and:

"It was a woman's voice," he answered.

"Great heavens!" I muttered--"what does it all mean?"

That the evidence of the cabman when he was discovered and of the
carter who had taken the box from the garage to the docks, and (for it
was possibly the same man) who had first delivered it at the Red
House, would but tighten the net about Isobel, whom I knew to be
innocent, I felt assured.

"Gatton," I said, "this case appears to me to resolve itself into a
deliberate conspiracy of which the end was not the assassination of
Sir Marcus, but the conviction of Miss Merlin!"

Gatton looked at me with evident complexity written all over him.

"I begin to think the same," he confessed. "This business was never
planned and carried out by a woman, I'll swear to that. There is a
woman concerned in it, for at every point we come upon evidence of her
voice issuing the mysterious instructions; but she is not alone in the
matter. Already the intricacy of the thing points to a criminal of
genius. When we know the whole truth, if we ever do, that the crime
was planned by a man of amazing, if perverted, intellect, will be put
beyond dispute, I think."