The walls oozed moisture, the candlelight showed her a pale slug about five inches long—Jane said six to start with, but, under pressure from Henry, retreated as far as five and would not yield another half-inch; she also said that the slug waved its horns at her and was crawling in her direction. Right there, as the Americans say, she made up her mind that this would be a good passage to explore with Henry, later on. She caught a glimpse of another slug on a level with the fifth step, whisked round, and ran.

“The one point about slugs is that they can’t run,” she said as she came back into the main corridor.

Without giving herself time to think, she plunged into the next opening on the left. It ran at right angles to the central passage, and was comparatively dry. It kept on the same level too, and Jane, trying to make a mental plan, thought that it must run under the house, cutting across the north wing. It occurred to her that there might be vaults of some kind under the terrace, and that this passage would perhaps lead to them. If this were so, it must soon either curve gradually to the left or take a sudden sharp turn. She wished she had thought of counting her steps, but it was difficult to pace regularly on a slippery floor and in such a poor light.

Just as she had begun to think that the passage must run out to sea, she came to the sharp turn which she had expected. A wall of black rock faced her, to her right a tunnel ran in at a sharp angle, and to her left there was a dark stone arch, a few feet of a new sort of tunnel built of brick, and then a steel gate exactly like the gates which shut off the laboratories in the house above.

Jane stared at the gate as if she expected it to dissolve into the surrounding darkness. The candle-light danced on the steel. It was rusty, but not so very rusty, and therefore it could not have been for very long in its present position. She came closer and touched it. It was real.

Her amazing good fortune almost overcame her. What a thing to tell Henry! What a justification for flouting his orders!! What a score!!!

Jane transferred the candle to her left hand, put out a right hand which trembled with excitement, and tried the gate. It was open. For a moment she drew back. Like the child who sits looking at a birthday parcel, the mere sight of which provides it with so many thrills that it cannot bring itself to cut the string and unwrap the paper, Jane stood and looked at her gate, her discovery—hers, not Henry’s.

As she looked, her eyes were caught by a small knob on the right-hand wall. It was about four feet above the floor and quite close to the steel bars. It was made of some dull metal and looked exactly like an electric-light switch. By going quite close to the gate and looking through she could see that a cased wire ran along the bricks on the same level, and she remembered that Henry had said the passages were wired.

Had Henry been first on the field after all? She turned, held her light high, and looked back. The wire went up to the roof and ran along until she lost it in the darkness. She reflected hopefully that Henry might have seen the wire much farther along, and turned back again.

Her fingers were on the switch when a really dreadful thought pricked her. Suppose the switch controlled some horrible explosive! It might turn on a light, most likely it did; but, on the other hand, it might let loose a raging demon of destruction that would blow the whole place to smithereens. It was an unreasonable thought, the sort of thought that one dismisses instantly in the daylight, but which by candlelight in an underground tunnel assumes a certain degree of credibility.