But Cleek took out a piece of chalk from his pocket.
"I need hardly tell you that a pentacle is a six-sided star very frequently used in masonry and the East," he said as they looked at him in some mystification.
"I knew that the murdered man was a member of the notorious Pentacle Club, since a pentacle was tattooed on his arm—Dr. Verrall will bear me out in that—and the pentacle was therefore in my mind's eye when I did this."
Kneeling, he swiftly joined up the points, and beneath the eyes of the interested watchers the white chalk marks, standing out clearly on the dark floor, grew into the ancient sign of a huge pentacle which spread across the centre of the room.
"Now," said Cleek, after they had surveyed his handiwork in amazement, "let us find the centre. And now look at this——"
Standing in the centre of the pentacle he stooped down and pressed hard on one of the little pieces of dark parquet.
As he did so a cry of astonishment broke from all those present, for a section of the floor, about the size of the space covered by a large tray, very gently sank in front of them, and they saw Cleek carried noiselessly and gently down into the darkness beneath.
Another minute and he was up again, a little smile on his face.
"When I discovered this," he went on, "it gave me plenty of food for thought and my further explorations still further solved the mystery. Mr. Narkom, if you will add your torch's gleam to mine it will give us light enough to complete my task. Come, you need not fear the lift will give way, it has carried down bigger and stranger burdens, I promise you."