One of these houses was my objective, and I soon found it, for its door was painted in a light shade, quite different from the hue of sombre respectability which characterised all its neighbours in the gloomy street. It was noticeable that while nearly every house in the street showed lights--the inmates had not yet got over their scare and could be heard volubly discussing the alarms and excursions of the night--this particular house was in total darkness and was as silent as the grave. I soon located a deep doorway from which I, myself unseen, could keep a close watch on the dark and silent house, and commenced my vigil. Presently a man wearing a long light overcoat turned from the square into Harrington Street, and, sauntering leisurely along, ascended the steps of the house I was watching, and let himself in with a latchkey. Five minutes later a second man passed close to where I was standing-- luckily my doorway was in deep shadow and he did not notice me--and also entered the house. Two others followed in quick succession. One of them I instantly recognised by his gait. It was Blind Heinrich! For four hours I kept surveillance, and during that time no fewer than seven men arrived, each letting himself in with his latchkey. It was evident we had found out the meeting-place of some highly doubtful individuals, whose obvious familiarity with the locality, coupled with the strange hours at which they arrived, indicated quite clearly that some nefarious scheme was afoot. It was evident, too, that the old Norwegian belonged to the gang. And I began to feel assured that our suspicions as to his real character were well founded. It would have been difficult to find a better place for the meeting, for Harrington Street, though readily accessible, led to nowhere in particular, and was as quiet a thoroughfare as any in London. No one would notice the arrival at intervals of the men, policemen rarely visited the street, and after midnight it was entirely deserted save for the occasional arrival home of some belated resident. It was not until five o'clock in the morning that the last man arrived in a taxi, which, however, did not come along the street, but deposited him at the corner of the Square. A quarter of an hour later they began to come out singly, at intervals of about five minutes, dispersing in different directions. There was no sign, however, of Heinrich Kristensten. "Well, _mon cher_ Gerald," said Madame Gabrielle, as she sat with me in my flat in Curzon Street, soon after breakfast the same morning. "You see they receive warning of coming air raids and meet directly after. Who are they?" "Enemy spies, beyond any possibility of doubt," I replied. "Our course is clear now. When the next raid is made we must follow them individually and learn each man's identity. I will make all the arrangements. Meanwhile, do you continue as you are and keep an eye on the blind fiddler."