"Here's a key," he said, holding toward me a small bright key; "just take it for the moment, Mr. Landon, as it is doubtless an important one."
"Where was it?" I asked.
"On the bed, by Mr. Pembroke's side. It had probably been under his pillow. It looks like the key of a safety box of some sort."
I put the key in my pocket, with a pleased thought that it would give me an opportunity to speak with Miss Pembroke. Meantime I noticed that Doctor Masterson's attitude was becoming more and more that of a greatly perplexed man.
"I don't understand it," he muttered. "A man can't die without a cause. And every known cause shows its own symptom. But I find no symptoms. What can this man have died of?"
"No foul play, I hope," I observed.
"No, no; nothing of that sort! Mr. Pembroke died peacefully in his sleep. But how?"
Suddenly he straightened himself up with an air of resolve.
"Is there a doctor living in this house?" he asked.