Anyhow she said good-bye to me with her usual cheerfulness and pluck, and we parted after a last affectionate kiss in full view of the open marsh.  Then I returned to the hut suffering from that novel and highly unpleasant sense of loneliness that Joyce’s departures had begun to awake in me.

I don’t think there is anything much more trying to one’s nerves than having to sit and wait for some critical event which may happen at any moment.  I have had a good deal of practice at waiting in my life, but I never remember the hours dragging so desperately slowly as they did the remainder of that afternoon.

A dozen times I went over what Latimer and Sonia had told me, putting together their different stories in my mind and trying to think if there was any point I had overlooked.  I could see none.  The mere way in which they had corroborated each other was enough to make me feel sure that they were both speaking the truth.  Besides, everything that had happened from the moment I had crept in through the kitchen window at McMurtrie’s house pointed to the same conclusion.

I may appear stupid not to have seen through the doctor earlier, but after all a gang of professional spies is hardly the sort of thing one expects to run up against in a Devonshire village.  A few years ago, indeed, I should have laughed at the idea of their existence anywhere outside the pages of a shilling shocker, but my three years in Dartmoor had led me to take a rather more generous view of what life can throw up in the way of scoundrels.

Whether they had killed Marks or not, I had little doubt now that they were wholly responsible for the attempt to murder Latimer.  Though I had good evidence that when it came to the point the two gentlemen on Sheppey didn’t stick at trifles, I could hardly fancy a couple of German Naval officers deliberately countenancing such methods.  If they had, they certainly deserved the worst fate that even Mr. Gow could wish them.

Somehow or other my private interest in the affair seemed to have been temporarily forced into the background.  I felt I was probably doing the best thing I could for myself in throwing in my lot with Latimer, but in any case his enthusiasm had got hold of me, and at all risks I was determined to stick to my side of the bargain.  I knew that in her heart Joyce would have hated me to do otherwise.

My chief danger, as she had instantly seen, was the chance of Sonia betraying me to the police.  The latter, who knew nothing of the part I was playing as a sort of unpaid bottle-washer to the Secret Service, would at once jump at the chance of arresting an escaped convict—­especially such a well-advertised one as myself.  However improbable Sonia’s story might sound, they would at least be certain to take the trouble to investigate it.

On the other hand, of course Sonia might not go to the police at all, and even if she did, it was quite possible that Latimer would strike first and so give me the chance of clearing out.