It seemed hopeless to pursue the inquiry any farther, but it was clear that in spite of Holmes’s ruse we had no proof that Barrymore had not been in London all the time. Suppose that it were so—suppose that the same man had been the last who had seen Sir Charles alive, and the first to dog the new heir when he returned to England. What then? Was he the agent of others or had he some sinister design of his own? What interest could he have in persecuting the Baskerville family? I thought of the strange warning clipped out of the leading article of the Times. Was that his work or was it possibly the doing of someone who was bent upon counteracting his schemes? The only conceivable motive was that which had been suggested by Sir Henry, that if the family could be scared away a comfortable and permanent home would be secured for the Barrymores. But surely such an explanation as that would be quite inadequate to account for the deep and subtle scheming which seemed to be weaving an invisible net round the young baronet. Holmes himself had said that no more complex case had come to him in all the long series of his sensational investigations. I prayed, as I walked back along the grey, lonely road, that my friend might soon be freed from his preoccupations and able to come down to take this heavy burden of responsibility from my shoulders.

Suddenly my thoughts were interrupted by the sound of running feet behind me and by a voice which called me by name. I turned, expecting to see Dr. Mortimer, but to my surprise it was a stranger who was pursuing me. He was a small, slim, clean-shaven, prim-faced man, flaxen-haired and lean-jawed, between thirty and forty years of age, dressed in a grey suit and wearing a straw hat. A tin box for botanical specimens hung over his shoulder and he carried a green butterfly-net in one of his hands.

“You will, I am sure, excuse my presumption, Dr. Watson,” said he as he came panting up to where I stood. “Here on the moor we are homely folk and do not wait for formal introductions. You may possibly have heard my name from our mutual friend, Mortimer. I am Stapleton, of Merripit House.”

“Your net and box would have told me as much,” said I, “for I knew that Mr. Stapleton was a naturalist. But how did you know me?”

“I have been calling on Mortimer, and he pointed you out to me from the window of his surgery as you passed. As our road lay the same way I thought that I would overtake you and introduce myself. I trust that Sir Henry is none the worse for his journey?”

“He is very well, thank you.”