“The door must come down,” he answered, and, springing against it, he put all his weight upon the lock. It creaked and groaned, but did not yield. Together we flung ourselves upon it once more, and this time it gave way with a sudden snap, and we found ourselves within Bartholomew Sholto’s chamber.

It appeared to have been fitted up as a chemical laboratory. A double line of glass-stoppered bottles was drawn up upon the wall opposite the door, and the table was littered over with Bunsen burners, test-tubes, and retorts. In the corners stood carboys of acid in wicker baskets. One of these appeared to leak or to have been broken, for a stream of dark-coloured liquid had trickled out from it, and the air was heavy with a peculiarly pungent, tar-like odour. A set of steps stood at one side of the room, in the midst of a litter of lath and plaster, and above them there was an opening in the ceiling large enough for a man to pass through. At the foot of the steps a long coil of rope was thrown carelessly together.

By the table, in a wooden arm-chair, the master of the house was seated all in a heap, with his head sunk upon his left shoulder, and that ghastly, inscrutable smile upon his face. He was stiff and cold, and had clearly been dead many hours. It seemed to me that not only his features but all his limbs were twisted and turned in the most fantastic fashion. By his hand upon the table there lay a peculiar instrument,—a brown, close-grained stick, with a stone head like a hammer, rudely lashed on with coarse twine. Beside it was a torn sheet of note-paper with some words scrawled upon it. Holmes glanced at it, and then handed it to me.

“You see,” he said, with a significant raising of the eyebrows.

In the light of the lantern I read, with a thrill of horror, “The sign of the four.”

“In God’s name, what does it all mean?” I asked.

“It means murder,” said he, stooping over the dead man. “Ah, I expected it. Look here!” He pointed to what looked like a long, dark thorn stuck in the skin just above the ear.

“It looks like a thorn,” said I.

“It is a thorn. You may pick it out. But be careful, for it is poisoned.”

I took it up between my finger and thumb. It came away from the skin so readily that hardly any mark was left behind. One tiny speck of blood showed where the puncture had been.

“This is all an insoluble mystery to me,” said I. “It grows darker instead of clearer.”

“On the contrary,” he answered, “it clears every instant. I only require a few missing links to have an entirely connected case.”