He pushed this door open and listened. Hearing nothing he passed on through it. He found himself in a broad corridor on to which gave the main staircase from below and its continuation to the upper floors. Three rooms opened on to this corridor, a large drawing-room, a small study and what was obviously the doctor's consulting room, from the operating table and the array of instruments set out in glass cases. The rooms were empty and Desmond was about to return to the back stairs and proceed to the next floor when his attention was caught by a series of framed photographs with which the walls of the corridor were lined.

These were groups of doctors taken at various medical congresses. You will find such photographs in many doctors' houses. Below each group were neatly printed the names of the persons therein represented. Anxious to see what manner of man was this Doctor Radcombe in whose house spies were apparently at liberty to consort with impunity, Desmond looked for his name.

There it was--Dr. A. J. Radcombe. But, on looking at the figure above the printed line, what was his astonishment to recognize the angular features and drooping moustache of "No. 13"!

There was no possible mistake about it. The photographs were excellent and Desmond had no difficulty in identifying the eccentric-looking German in each of them. So this was Mrs. Malplaquet's house, was it? A nursing-home run by "No. 13," who in addition to being a spy, would seem to have been a nerve specialist as well. In this guise, no doubt, he had made trips to the South of England which had gained for him that intimate acquaintance with Portsmouth and Southsea of which he had boasted at the gathering in the library. In this capacity, moreover, he had probably met Bellward whose "oggult" powers, to which "No. 13" had alluded, seem to point to mesmerism and kindred practices in which German neurasthenic research has made such immense progress.

Pondering over his surprising discovery, Desmond pursued his way to the floor above. Here, too, was a green baize door which opened on to a corridor. Desmond walked quickly along it, glancing in, as he passed, at the open doors of two or three bedrooms. Just beyond where the staircase crossed the corridor were two doors, both of which were closed. The one was a white door and might have been a bathroom; the other was enameled a brilliant, glossy red.

The second floor was as silent and deserted as the corridor below. But just as Desmond passed the head of the main staircase he heard the sound of voices. He glanced cautiously down the well of the stairs and saw Strangwise and Bellward talking together. Bellward was on the stairs while Strangwise stood in the corridor.

"It's our last chance," Strangwise was saying.

"No, no," Bellward replied heatedly, " I tell you it is madness. We must not delay a minute. For Heaven's sake, leave the girl alone and let's save ourselves."