It was written upon the note-paper I knew so well, stamped with the neat address “Neneford,” in black, but bearing no date. What I read was as follows:—
“Sir,—I fail to comprehend the meaning of your words when you followed me into the train at Huntingdon last night. I am in no fear of any catastrophe; therefore I can only take your offer of assistance as an attempt to obtain money from me. If you presume to address me again I shall have no other course than to acquaint the police.
”Yours truly
“Mary Courtenay.”
“Ah!” I exclaimed. “Then he warned her, and she misunderstood his intention.”
“Without a doubt,” said Ambler, taking the letter from my hand. “This was written probably only a few days before her death. That man,” and he glanced at the prostrate body, “was the only one who could give us the clue by which to unravel the mystery.”
But the dead man’s lips had closed, and his secret was held for ever. Only those letters remained to connect him with the river tragedy; or rather to show that he had communicated with the unfortunate Mrs. Courtenay.
In company we walked to Leman Street Police Station, one of the chief centres of the Metropolitan Police in the East End, and there, in an upper office, Ambler had a long consultation with the sergeant of the Criminal Investigation Department.
I described the appearance of the body, and stated my suspicions of poisoning, all of which the detective carefully noted before going forth to make his own examination. My address was taken, so that I might assist at the post-mortem, and then, shortly after midnight I drove back westward through the City with Ambler at my side.
He spoke little, and when in Oxford Street, just at the corner of Newman Street, he descended, wished me a hurried good-night, and disappeared into the darkness. He was often given to strange vagaries of erratic movement. It was as though some thought had suddenly occurred to him, and he acted at once upon it.