I debated with myself whether it would be best to let McMurtrie know that the place was being watched.  To a certain extent his interests in the matter seemed to be identical with mine, but my mistrust of him was still strong enough to make me hesitate.  Beyond his bare word and that of Sonia I had no proof as yet that he intended to play straight with me.

One thing appeared certain, and that was that Latimer had failed to recognize me as the man who had sent him the warning at Parelli’s.  In a way this gave me an advantage, but it was a forlorn enough sort of advantage in view of the unknown dangers by which I was surrounded.

I got up off the bed, feeling anything but comfortable, and going to the door had another look round.  Latimer had disappeared behind the thin belt of trees that fringed the Tilbury road, and so far as I could see there was no one else about.  Getting out my keys, I walked along to the shed and opened the door.

If my living accommodation was a trifle crude, McMurtrie had certainly made up for it here.  He had evidently carried out my instructions with the most minute care and an absolute disregard for expense.  Lead tanks, sinks, chemicals, an adequate water supply in the shape of a pump—­everything I had asked for seemed to have been provided.  I looked round the large, clean, well-lighted place with a sensation of intense satisfaction.  The mere sight of all these preparations made me ache to begin work, for I was consumed with the impatience that any inventor would feel who had been compelled to leave a big discovery on the very verge of completion.

Coming out, I closed the door again, and carefully turned the key behind me.  Then walking back to the hut I locked that up as well.  I hadn’t the faintest belief in Latimer’s story about finding the place open, and apart from making things safe I certainly didn’t want to leave any traces of my surprise visit.  From what I knew of McMurtrie I felt sure that he had left somebody in charge, and that in all probability Latimer had merely taken advantage of their temporary absence.

After a last glance all round, to make sure that the coast was still clear, I walked rapidly down to the sea-wall and scrambled up on to the top.  The tide had risen a bit, but there was just room to get along, so jumping down I set off on my return journey.

There was something very cheering and reassuring in the sight of the Betty riding easily at her anchor, as I made my way round the mouth of the creek.  Tommy and Joyce were both on deck:  the former in his shirt-sleeves, swabbing down his new paint with a wet mop.  Directly he saw me he abandoned the job to Joyce, and with a wave of his hand proceeded to get out the dinghy.  A minute later he was pulling for the shore.

“All serene?” he inquired calmly, as he ran the boat up to where I was standing.

“Yes,” I said.  “We needn’t hurry; there’s no one chasing me.”  Then pushing her off the mud I jumped in.  “I’ll tell you the news,” I added, “when we get on board.”