"We shall find a man on duty," whispered T. B.; "he is patrolling the house, and I have an idea that there are trip-wires on the lawn."
He had fixed a funnel-like arrangement to the head of his lamp, and now he carefully scrutinized the ground as he walked forward. The funnel was so fixed that it showed no light save on the actual patch of ground he was surveying.
"Here is one," he said, suddenly.
The party stepped cautiously over the almost invisible line of wire, supported a few inches from the ground by steel uprights, placed at regular intervals.
"They fix these every night after sunset; I have watched them doing it," said T. B. "There is another line nearer the house."
They found this, too, and carefully negotiated it.
"Down!" whispered T. B. suddenly, and the party sank flat on the turf.
Ela for a moment could not see the cause for alarm, but presently he discerned the slow moving figure of the sentry as it passed between them and the house. The man was walking leisurely along, and even in the starlight they could see the short rifle slung at his shoulder. They waited until he had disappeared round the corner of the house, and then crossed the remaining space of lawn. T. B. had been carrying a little canvas bag, and now he put his hand inside and withdrew by the ears a struggling rabbit.
"Little friend," he whispered, "You must be sacrificed in the cause of scientific criminal investigation."
He mounted the steps which led to the entrance hall. The steel-beaded curtain still hung before the door almost brushing the mat as he had seen it. He released the rabbit, and the startled beast, after a vain attempt to escape back to the lawn, went with hesitating hop on to the mat, and then, at a threatening gesture from T. B., pushed his nose to the hanging curtain to penetrate his way to safety. Instantly as he touched it there was a quick flicker of blue light, and the unfortunate animal was hurled back past T. B. to the gravel path below. The detective descended hastily and picked it up. It was quite dead. He felt the singed hair about its head, and murmured a sympathetic "vale."