Just before eleven that same night I strolled past the house of Hermann Hartmann, in Pont Street, vaguely wondering what I could do to prevent a theft which must, I knew, shortly be committed. In all probability the ingenious Hartmann already had a secret agent in Joynson's works, but even if he had, he would certainly not be able to discover the secret. I had quite satisfied myself upon that point. No, the peril lay in the Professor himself--the strange old pig-headed patriot. Scarcely had I passed Hartmann's house, the exterior of which I knew so well, when I heard the front door close and saw a man coming down the steps. As he walked in my direction I halted beneath a lamp to light a cigarette, and by so doing I obtained a glimpse of his face as he passed. He was a young, good-looking, smartly dressed man, with dark eyes and hair and a rather sallow complexion. I put him down to be an Italian, but I had never set eyes upon him before. No doubt he was one of Hartmann's travelling agents--a man who went up and down England visiting the fixed spies of Germany, or "letter-boxes," as they are known in the bureau of secret police in Berlin--collecting their reports and making payments for information or services rendered. Knowing so much of the ways of the German secret agent, curiosity prompted me to follow him. He strolled as far as the corner of Sloane Street and Knightsbridge, and then boarded a motor-bus as far as Piccadilly Circus. Thence he walked to the German beer-hall, the Gambrinus, just off Coventry Street, where he joined a tall, thin, grey-moustached man, an Italian like himself, who was seated awaiting him. I idled across to a table close by, called for beer, and sat smoking a cigarette and straining my ears to catch their conversation, which was in Italian, a language I know fairly well. I discovered the following facts. The thin-faced man was called Giovanni, while the elegant young fellow was Uberto, and they were discussing the arrival of somebody. Giovanni seemed dubious about something, while the man who had left Hartmann's seemed enthusiastic. After a quarter of an hour Uberto glanced at his watch, made some remark to his companion, and they rose and went out together, driving in a taxicab westward, I following in another, which I fortunately found just in time. Through Kensington we went, over Hammersmith Bridge, through Barnes, and across the Common. Then I realised we were going to Richmond. The chase grew exciting. Before me I could see the red back-lamp of the taxi as it sped forward, and half an hour later we were crossing Richmond Bridge, where, a short distance along the road to Twickenham, they suddenly swung round to the left into St. Margaret's and pulled up before a good-sized detached house which stood back in its own grounds, in which were several big trees. The thoroughfare was, I noted, called Brunswick road.