Peering in, we could see that the only light in the room came from a dull blue flame which flickered from a small brass tripod in the centre. It threw a livid, unnatural circle upon the floor, while in the shadows beyond we saw the vague loom of two figures which crouched against the wall. From the open door there reeked a horrible poisonous exhalation which set us gasping and coughing. Holmes rushed to the top of the stairs to draw in the fresh air, and then, dashing into the room, he threw up the window and hurled the brazen tripod out into the garden.

“We can enter in a minute,” he gasped, darting out again. “Where is a candle? I doubt if we could strike a match in that atmosphere. Hold the light at the door and we shall get them out, Mycroft, now!”