It was half an hour before Drummond decided that it was safe to start exploring. The moon still shone fitfully through the trees, but since the two car watchers were near the road on the other side of the house, there was but little danger to be apprehended from them. First he took off his shoes, and tying the laces together, he slung them round his neck. Then, as silently as he could, he commenced to scramble upwards.
It was not an easy operation; one slip and nothing could have stopped him slithering down and finally crashing into the garden below, with a broken leg, at the very least, for his pains. In addition, there was the risk of dislodging a slate, an unwise proceeding in a house where most of the occupants slept with one eye open. But at last he got his hands over the ridge of the roof, and in another moment he was sitting straddle-wise across it.
The house, he discovered, was built on a peculiar design. The ridge on which he sat continued at the same height all round the top of the roof, and formed, roughly, the four sides of a square. In the middle the roof sloped down to a flat space from which stuck up a glass structure, the top of which was some five or six feet below his level. Around it was a space quite large enough to walk in comfort; in fact, on two sides there was plenty of room for a deck chair. The whole area was completely screened from view, except to anyone in an aeroplane. And what struck him still further was that there was no window that