He rose from his knees, and walked slowly across to the
mantelpiece, where he stood abstractedly fingering the ornaments,
and straightening them--a trick of his when he was agitated.

"Mon ami," he said, turning to me, "somebody stepped on that cup,
grinding it to powder, and the reason they did so was either
because it contained strychnine or--which is far more
serious--because it did not contain strychnine!"

I made no reply. I was bewildered, but I knew that it was no
good asking him to explain. In a moment or two he roused
himself, and went on with his investigations. He picked up the
bunch of keys from the floor, and twirling them round in his
fingers finally selected one, very bright and shining, which he
tried in the lock of the purple despatch-case. It fitted, and he
opened the box, but after a moment's hesitation, closed and
relocked it, and slipped the bunch of keys, as well as the key
that had originally stood in the lock, into his own pocket.

"I have no authority to go through these papers. But it should
be done--at once!"

He then made a very careful examination of the drawers of the
wash-stand. Crossing the room to the left-hand window, a round
stain, hardly visible on the dark brown carpet, seemed to
interest him particularly. He went down on his knees, examining
it minutely--even going so far as to smell it.

Finally, he poured a few drops of the coco into a test tube,