As I was speaking I took from beneath some letters, still remaining in the secret drawer Boyd had opened, a wooden pill-box, from which I removed the lid, there being disclosed a small quantity of a peculiar greyish-blue powder.
“Hulloa!” Boyd exclaimed, with a quick glance at it. “What’s that, I wonder? No label on the box. It looks suspicious!”
“Yes,” I agreed. “I wonder what it is, that it should be so carefully concealed?”
“Leave it aside for a moment,” he said.
Then taking up a large envelope which, while I had been reading the letters, he had been carefully examining, he drew from it two photographs.
“Do you recognise the originals of these?” he inquired with a grave smile.
“Great Heavens!” I gasped. “Why, they are the man and the woman whom we found at Phillimore Place!”
“Exactly,” he said, in a voice of satisfaction, just as his assistant re-entered.
Then, before I could recover from my bewilderment, he took up the little wooden box, exclaiming—
“This powder here is a very suspicious circumstance, but we’ll test it at once.”