"Shackleton was undoubtedly a foreigner and I should say probably a German," the watchmaker, now a corporal, told me. "When he left he asked me to forward any letters that might come for him, and gave me the address--`Care of Soulsby, High Street, Bristol.'" With that information I went straight from the British front to the great Severn port. Here I found that Soulsby kept a newsagent's shop near Bristol Bridge, to which letters could be addressed. He did a big business in this way, for the address was very handy for sea-going men. Soulsby at first refused to give me the smallest information about his clients, but a sight of my authority opened his mouth, and as soon as he realised that something serious was on foot he was only too willing to help me. "Of course, Mr Sant," he said, "you will understand I have no knowledge whatever of the man. But I know that the Bristol Channel ports are full of spies, and it is very generally believed that few vessels leave here unknown to the German submarines lurking about the mouth of the Channel. If I can help you at all, I shall be delighted." I then learned that Shackleton had called about a week before, taking away several letters addressed to him, and that he usually called at intervals of a week or ten days. Soulsby promised to let me know at once as soon as he came again, and I wired to the wily Aubert to come to Bristol and keep observation. Within three days, as I walked with my assistant along Victoria Street towards Temple Meads, he pointed out a middle-aged, keen-eyed, dark-haired man, who had little of the appearance of a Teuton. He looked like a well-dressed, prosperous business man. Yet it was he who had induced the unfortunate Pasquet to steal the herbethite, and he was certainly engaged in some nefarious and deadly plot. For although the actual volume of the stolen explosive was not great, so tremendous was its power that the quantity in the hands of our foes was sufficient to wreak almost unimaginable havoc in half a dozen cities in England. Mr Herbeth had looked very grave when he learned from Pasquet through me that the amount stolen was enough to fill two of the small cans used to hold golden syrup--about a pint and a half altogether. "I hope monsieur will trace it in time," he said earnestly. "There is enough of it in their possession to destroy half London." We soon found out that Shackleton was living in furnished rooms at Clifton and had one close friend, who, after some difficulty, we proved to be his accomplice Norman. One morning Aubert arrived at my hotel and reported that the pair had gone to the station and taken tickets for London. At once I advised Madame Gabrielle by telephone to be on the platform at Paddington and watch them wherever they went. I myself took the next train to London, and, driving to Curzon Street, awaited her report.