Dr. Emerson thought for some moments.

“Well,” he said at last, “I must admit that murder is possible, though I don’t for a moment believe death occurred otherwise than as I said. As to possible methods, there were no obvious wounds on the body and violence in the literal sense is therefore unlikely. A sharp blow over the heart or on the stomach might have caused heart failure without leaving physical marks, but in such a case the features would have looked distressed. For the same reason death from the shock of a sudden fright or start may be ruled out. It is of course true that certain kinds of poison might have been administered. A whiff of hydrocyanic acid gas would cause almost instantaneous death and produce the same appearance as death from natural causes. An injection of cocaine would do the same where there was heart disease, and there are other similar agents. But in these cases the difficulty of the average man in obtaining the substances in question and also in knowing how to use them if obtained, is so great that I think they might all be ruled out. No, Inspector, amazing as your discovery seems, I cannot think you are right in assuming murder.”

“But,” thought French, though he did not put his thought into words, “if the man you suspect spent the best years of his life as male nurse in a medical institution, these difficulties pretty well vanish.” But he concealed his satisfaction, and, instead, simulated disappointment.

“That seems very reasonable, doctor, I must admit. At the same time I shall have to put inquiries in hand as to whether any one recently tried to obtain cocaine or those other things you have mentioned. Of course, I don’t say that necessarily I am right in my ideas.”

“I don’t think you are right, though I confess I’m absolutely lost in amazement about that coffin. Come now, Inspector, you must know more than you pretend. Are your ideas hopelessly confidential?”

French shook his head, then said, “I can tell you, doctor, that I know nothing more than I have already mentioned. I may have a surmise, but you will agree that I could not repeat mere surmises which might also be slanders against perfectly innocent persons. If I find that my theories seem to have a basis on fact I may ask for your further help, but at present I see no signs of that. You’ll agree that I’m right?”

Emerson admitted it, and after some further conversation French took his leave. So far everything was going satisfactorily. Each new fact which he learned tended to strengthen his theory. And incidentally and unexpectedly he had come on another piece of evidence, circumstantial of course, but none the less strong. According to Dr. Emerson, the murder was most likely to have been committed by methods which Roper alone, of all the people that French could think of, had the knowledge and the ability to employ. French’s satisfaction was intense as he noted the cumulative effect of his discoveries. By this method of cumulative circumstantial evidence was he accustomed to find suspicion grow to certainty and certainty to proof.

So much for the first of the two inquiries French had set himself to make. There remained the investigation of the late Markham Giles’ cottage, and after a snack of early lunch at the hotel, he started out along the Starvel road.

It was dull and rather cold, but a pleasant day for walking. French tramped along, enjoying the motion and the extended view offered by the wide, open spaces of the moor. Though, owing to the atmosphere, the colouring was neither so warm nor so rich as it had previously appeared, there was a fascination in the scenery which strongly appealed to him. He had found a similar though keener charm in Dartmoor, which he had once explored on the occasion of a visit to a cracksman doing time in the great prison at Princetown. Indeed Dartmoor and Exmoor both figured on his list of places to be visited when time and money should permit.

Diverging from the Starvel road at the point where Ruth Averill and Mrs. Oxley had joined the deceased man’s funeral, French skirted the edge of the Hollow and in a few minutes reached the cottage. It was a tiny box of a place, but strongly built, with stone walls and slated roof. Its architecture was of the most rudimentary kind, a door and two windows in front and at the back being the only relieving features in the design. The house stood a short distance back from the road in the middle of a patch of cultivated ground. Behind was a row of wooden beehives.