“Of course, madam, with your permission,” he answered. “It is a complex case. When we have solved it we shall then know how to treat the young lady.”

“And how do you intend to begin?” I inquired, raising myself, not without considerable difficulty.

“By going into the room alone,” he answered briefly.

“You, too, will risk your life?” I exclaimed. “Is it wise?”

“Research is always wisdom,” he responded. Then, finding that I was recovering rapidly from the seizure, he gave me some technical direction how to treat him in case he lost consciousness.

He arranged the tiny syringe, and the various drugs and tabloids, upon the hall table, and then, with a final examination of them, he opened the door of the fatal room and entered, leaving us standing together on the threshold.

Walking to the window he looked out, afterwards making several tours of the room in search of its secret. He, however, found nothing. The air was pure as London air can be on a summer’s night, and, as far as either of us could discern, there was nothing unusual in the department. The door swung to halfway, and we heard him growling and grunting within. He remained in the room for perhaps five minutes, then emerged.

Scarcely, however, had he crossed the threshold when he lifted his left arm suddenly, crying—

“Ach, Gott! I am seized. The injection—quick!”

His fleshy face went pale, and I saw by its contortions that the left side had become paralysed. But with a quick movement I pushed up his coat-sleeve, and ran the needle beneath the skin.