about the _Betty_ if necessary. J."

I thrust it into my pocket and opened the other.

"A copper come last nite and ask for you. He see Misses O."

For an instant I stared at this cryptic message in bewilderment; then
suddenly the recollection of my final instructions to Gertie 'Uggins
rushed into my mind.

So Sonia _had_ gone to the police, or had at least contrived to send
them a message which served the same purpose. Their visit to Edith
Terrace was probably explained by the fact that she had given them
both addresses so as better to establish the truth of her story.
Anyhow the murder was out, and with a new and not unpleasant thrill
of excitement I crushed up Gertie's wire in my hand and tore open
McMurtrie's letter.

"DEAR MR. NICHOLSON,

"I have been away on business and have only just received your letter,
otherwise I should have come to see you this afternoon. In the first
place allow me to congratulate you most heartily on your success, of
which personally I was never in any doubt.

"For the moment I have left the Hotel Russell, and am staying with
some friends in Sheppey. I shall run up the river in their launch
early tomorrow morning, as I believe there is a small creek close to
the hut where we can put in.

"Please have a specimen of the powder ready, and if it is possible I
should like you to arrange for an actual demonstration, as I shall
have a friend with me who is already considerably interested in our
little company, and would be prepared to put up further capital if
convinced of the merits of your invention.

"You can expect us about high water, between half-past nine and ten.

"Your sincere friend,

"L.J. McMURTRIE."

As I read the signature McMurtrie's smiling mask-like face seemed
suddenly to rise up in front of me, and all my old instincts of
distrust and repulsion came to keep it company. So he was at the
bungalow, and in little over an hour he would be here--he and the
mysterious friend who was "already considerably interested in
our little company." I smiled grimly at the phrase; it was so
characteristic of the doctor; though when he wrote it he could little
have guessed how thoroughly I should be able to appreciate it.

He was also equally ignorant of the complications introduced into
the affair by Sonia. Unless I had been altogether misled by Gertie's
message, it was probable that the police were even now on their way to
arrest me, just as McMurtrie's launch was most likely s