After breakfast, we both strolled round to the factory. The ground it covered was not much, and it was surrounded by a wall about twelve feet high, so that no one could see within the courtyard. It had, at one time, been a lead-mill, but for the past eight years had, we learned, been untenanted. Even as we loitered near, we saw the builder's men bringing long ladders for the inspection of the chimney. We watched for a whole week, but as each day passed, I became more confident that we were upon a false scent. The chimney had been inspected, the ladders taken down again, and once more the German and the Belgian had returned south to that pleasant London suburb. In order to ascertain what was really in progress I called one morning upon the solicitor in Whitefriargate, on pretext of being a likely tenant of the factory. I was, however, informed by the managing clerk that it was already let to a firm of electrical engineers. Thus the purchase of electrical appliances was entirely accounted for. Once again I returned to London. They seemed, by the electrical accessories that had been delivered, to be fitting up a second factory in their house in Sydenham. That, being a private house, seemed somewhat mysterious. They had become friendly also with a tall, rather well-dressed Englishman named Fowler, who had the appearance of a superior clerk, and who resided in a rather nice house in Hopton Road, Streatham Hill. Fowler had become a frequent visitor at their house, while, on several occasions, he dined with Dubois at De Keyser's Hotel, facing Blackfriars Bridge. In consequence of some conversation I one evening overheard--a conversation in English, which the Belgian spoke fluently--I judged Fowler to be an electrician, and it seemed, later on, very much as though he had been, or was about to be, taken into partnership with them. As far as we could discover, however, he had been told nothing about the factory in Hull. More than once I suspected that the two foreigners were swindlers, who intended to "do" the Englishman out of his money. This was impressed I upon me the more, because one evening a German woman was introduced to their newly-found friend as Frau Gessner, who had just arrived from Wiesbaden. Whether she was really Gessner's wife I doubted. It was curious that, on keeping observation that evening, I found that the lady did not reside at Sydenham, but at a small hotel in Bloomsbury, not a stone's-throw from my own rooms. There was certainly some deep game in progress. What could it be? Vera had watched Fowler on several occasions, but beyond the fact that he was an electrical engineer, occupying a responsible position with a well-known telegraph construction company, we could discover nothing.