"As I suspected," he said in a low voice, "an electric death-trap for anybody trying to get into the house that way. Now, Johnson."

The third man was busy pulling out a pair of rubber boots; he took from his pocket a pair of thick rubber gloves, and made his way with confidence up the steps. He leant down and tried to pull the mat from its place, but that was impossible. He gathered up the beads cautiously with his hands; he was free, by reason of his boots and his hand-covering, from the danger of a shock, but he took good care that no portion of the curtain touched any other part of his body. Very cautiously he drew the bead "chick" aside, looping it back by means of strong rubber bands, and then T. B. went forward. In the meantime he had followed the other's example, and had drawn stout rubber goloshes over his feet and had put on gloves of a similar material. The lock that he had noticed earlier in the day was of a commonplace type; the only danger was that the inmates had taken the precaution of bolting or chaining the door, but apparently they were content with the protection which their electric curtain might reasonably be expected to afford. The door opened after a brief manipulation of keys, and T. B. stepped into the hall. He listened, all his senses strained, for the sound of a warning bell, but none came. Ela and the other man followed.

"Better remain in the hall," said T. B. "We shall have to chance the guard not noticing what has happened to the curtain, anyway; perhaps he will not be round for some time," he added, hopefully.

They made a quick scrutiny of the hall, and found no indication of cables or of wires which would suggest that an alarm had been fixed. T. B. stole carefully up the stairs, leaving the two men to guard the hall below. At every landing he halted, and listened, but the house was wrapped in silence, and he searched the third floor without mishap.

He recognized the corridor, having taken very careful note of certain peculiarities, and a scratch on the side of the lift door, which he had mentally noted for future reference, showed him he was on the right track.

Unerringly and swiftly he passed along the passage till he came to the big rosewood doors which opened upon the invalid's bedroom. He turned the handle gently, it yielded, and he stepped noiselessly through the door, and pushed the inner door cautiously. The room was dimly illuminated, evidently by a night light, thought T. B., and he pressed the door farther open that he might secure a better view of the apartment, and then he gasped, for this was not the room he had been in before.

It was a sumptuously arranged bureau, panelled in rosewood, and set about with costly furniture. A man was sitting at the desk, busily writing by the light of a table lamp; his back was toward T. B. The detective pushed the door farther open, and suddenly the man at the desk leapt up, and turning round, confronted the midnight visitor.

T. B. had only time to see that his face was hidden behind a black mask which extended from his forehead to his chin. As soon as he saw T. B. standing in the doorway, he reached out his hand. Instantly the room was in darkness, and the door, which T. B. was holding ajar, was suddenly forced back as if by an irresistible power, flinging the detective into the corridor, which almost simultaneously was flooded with light. T. B. turned to meet the smiling face of Dr. Fall.

The big man, with his white, expressionless countenance, was regarding him gravely, and with amused resentment.