gave a few final instructions to Ellis, who was also staying
behind, and then the four of us left the bungalow and walked quietly
down the small garden path that led to the road. Just outside the gate
stood a powerful five-seated car.

"Start her up, Guthrie," said Latimer; and then turning to us, he
added, with a smile: "I want you in front with me, Lyndon. I know
Morrison's dying for a yarn with you, but he must wait."

Tommy nodded contentedly. "I can wait," he observed; "it's a habit
I've cultivated where Neil's concerned."

We all clambered into the car, and, slipping in his clutch Latimer set
off at a rapid pace in the direction of Queenborough. It was not until
we had rounded the first corner that he opened the conversation.

"How did you know about Marks?" he asked, in that easy drawling voice
of his.

"I didn't know for certain," I said quietly. "It was more or less of a
lucky shot."

Then, as he seemed to be waiting for a further explanation, I repeated
to him as briefly as possible what Sonia had told me about McMurtrie's
reason for visiting London.

"I didn't go into all this in my letter to you," I finished, "because
in the first place there was only just time for Joyce to catch the
train, and in the second I didn't want to disappoint her in case it
should turn out to be all bunkum. You must have been rather amazed
when I suddenly sprung it on McMurtrie."

He shook his head, smiling. "Oh no," he said--"hardly amazed." He
paused. "You see, I knew about it already," he added placidly.

If there was any amazement to spare at that moment it was certainly
mine.

"You knew about it!" I repeated. "You knew that McMurtrie had killed
Marks?"

He nodded coolly. "You remember telling me in the boat that your
friend Miss--Miss Aylmer, isn't it?--had recognized him as the man she
saw at the flat on the day of the murder?"

"Yes," I said.

"Well, if that was so, and you had been wrongly convicted, which I
was inclined to believe, the doctor's presence on the scene seemed to
require a little looking into. I knew that at that time he had only
just arrived in London, so the odds were that he and Marks were old
acquaintances. I hunted up the evidence in your trial--I had rather
forgotten it--and I found just what I expected. Beyond the fact that
Marks was a foreigner and had been living in London for about eight
years, no one seemed to know anything about him at all. The police
were so confident in their ca