We all followed him into the housekeeper’s room, which stood upon the left-hand side of the passage. The old woman was pacing up and down with a scared look and restless, picking fingers, but the sight of Miss Morstan appeared to have a soothing effect upon her.

“God bless your sweet, calm face!” she cried with a hysterical sob. “It does me good to see you. Oh, but I have been sorely tried this day!”

Our companion patted her thin, work-worn hand and murmured some few words of kindly, womanly comfort which brought the colour back into the other’s bloodless cheeks.

“Master has locked himself in and will not answer me,” she explained. “All day I have waited to hear from him, for he often likes to be alone; but an hour ago I feared that something was amiss, so I went up and peeped through the keyhole. You must go up, Mr. Thaddeus—you must go up and look for yourself. I have seen Mr. Bartholomew Sholto in joy and in sorrow for ten long years, but I never saw him with such a face on him as that.”

Sherlock Holmes took the lamp and led the way, for Thaddeus Sholto’s teeth were chattering in his head. So shaken was he that I had to pass my hand under his arm as we went up the stairs, for his knees were trembling under him. Twice as we ascended, Holmes whipped his lens out of his pocket and carefully examined marks which appeared to me to be mere shapeless smudges of dust upon the cocoanut- matting which served as a stair-carpet. He walked slowly from step to step, holding the lamp low, and shooting keen glances to right and left. Miss Morstan had remained behind with the frightened housekeeper.

The third flight of stairs ended in a straight passage of some length, with a great picture in Indian tapestry upon the right of it and three doors upon the left. Holmes advanced along it in the same slow and methodical way, while we kept close at his heels, with our long black shadows streaming backward down the corridor. The third door was that which we were seeking. Holmes knocked without receiving any answer, and then tried to turn the handle and force it open. It was locked on the inside, however, and by a broad and powerful bolt, as we could see when we set our lamp up against it. The key being turned, however, the hole was not entirely closed. Sherlock Holmes bent down to it and instantly rose again with a sharp intaking of the breath.

“There is something devilish in this, Watson,” said he, more moved than I had ever before seen him. “What do you make of it?”

I stooped to the hole and recoiled in horror. Moonlight was streaming into the room, and it was bright with a vague and shifty radiance. Looking straight at me and suspended, as it were, in the air, for all beneath was in shadow, there hung a face—the very face of our companion Thaddeus. There was the same high, shining head, the same circular bristle of red hair, the same bloodless countenance. The features were set, however, in a horrible smile, a fixed and unnatural grin, which in that still and moonlit room was more jarring to the nerves than any scowl or contortion. So like was the face to that of our little friend that I looked round at him to make sure that he was indeed with us. Then I recalled to mind that he had mentioned to us that his brother and he were twins.

“This is terrible!” I said to Holmes. “What is to be done?”

“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