The husband strolled up by this time, and entered into conversation with us. According to his own account, his name was Forbes-Gaskell, and he was a Professor of Geology in one of those new-fangled northern colleges. He had come to Seldon rock-spying, he said, and found much to interest him. He was fond of fossils, but his special hobby was rocks and minerals. He knew a vast deal about cairngorms and agates and such-like pretty things, and showed Charles quartz and felspar and red cornelian, and I don't know what else, in the crags on the hillside. Charles pretended to listen to him with the deepest interest and even respect, never for a moment letting him guess he knew for what purpose this show of knowledge had been recently acquired. If we were ever to catch the man, we must not allow him to see we suspected him. So Charles played a dark game. He swallowed the geologist whole without question. Most of that morning we spent with them on the hillside. Charles took them everywhere and showed them everything. He pretended to be polite to the scientific man, and he was really polite, most polite, to the poetical lady. Before lunch time we had become quite friends. The Clays were always easy people to get on with; and, bar their roguery, we could not deny they were delightful companions. Charles asked them in to lunch. They accepted willingly. He introduced them to Amelia with sundry raisings of his eyebrows and contortions of his mouth. "Professor and Mrs. Forbes-Gaskell," he said, half-dislocating his jaw with his violent efforts. "They're stopping at the inn, dear. I've been showing them over the place, and they're good enough to say they'll drop in and take a share in our cold roast mutton;" which was a frequent form of Charles's pleasantry. Amelia sent them upstairs to wash their hands--which, in the Professor's case, was certainly desirable, for his fingers were grimed with earth and dust from the rocks he had been investigating. As soon as we were left alone Charles drew me into the library. "Seymour," he said, "more than ever there is a need for us strictly to avoid preconceptions. We must not make up our minds that this man is Colonel Clay--nor, again, that he isn't. We must remember that we have been mistaken in _both_ ways in the past, and must avoid our old errors. I shall hold myself in readiness for either event--and a policeman in readiness to arrest them, if necessary!" "A capital plan," I murmured. "Still, if I may venture a suggestion, in what way are these two people endeavouring to entrap us? They have no scheme on hand--no schloss, no amalgamation."