"No, only that it was taken furnished by a gentleman a month ago--a foreigner whose description exactly tallies with that of Hartmann--for an old man and his daughter--both Italians. They've kept themselves very much to themselves, therefore the neighbours know practically nothing about their business." "Well, Nella Emden was enticed in there. I'm certain of that," I said. "Yet the fact that she's in Liverpool rather negatives my first theory of foul play," I added. "Yes. But we must still remain watchful. Vera has gone to make some inquiries for me over at Mortlake. I expect her back in half an hour. You return and keep a watchful eye upon the Professor's place. One never knows what crooked business may be on hand!" So back I went, and through the whole evening waited there, chilled to the bone, in vain expectancy. I had noticed from Ray's manner that he had become very suspicious. He somehow scented the presence of spies at times when, I confess, I felt calm and reassured. And his natural intuition was seldom, if ever, wrong. The church bells across the river had chimed midnight, the Professor's servants had put out the lights and retired, and the thoroughfare was now deserted. Hungry and tired out, I was contemplating relaxing my vigil when Ray suddenly turned a corner and joined me, saying breathlessly: "Uberto and his friend are coming up the hill with another man. Vera and I have seen them call at Brunswick Road, and they are now on their way here. We must keep a strict watch. Something is up!" We separated, and concealing ourselves in the basements of the houses opposite, we witnessed that which caused our heart-beats to quicken. The three men came along in silence in the night, for they evidently wore rubber heels on their boots. The constable was then some distance down the hill, therefore they passed him. As they approached the house, the man whom I had heard addressed as Giovanni hurried forward, and slipping suddenly into the narrow front garden, approached the kitchen window. Inserting something between the sashes, he pushed back the latch, carefully drew back the blind, and was within the house almost before the two others had entered the garden. Then, without a sound, the pair followed him. Indeed, the three spies had entered the premises so quickly that we could scarcely believe our own eyes. "The police!" whispered Ray. "We must get the constable. Slip down the hill and tell him. We'll make a fine capture this time!" Down the hill I sped, and five minutes later was back with the constable, having briefly explained to him our suspicions. "I don't know anything about German spies, sir, but whoever's inside is liable for burglariously entering, and we'll have 'em," whispered the officer. Silently we entered just as the spies had done, passing through the kitchen, and up the stairs. The laboratory was at the top of the house I knew, and was always kept locked. Therefore we crept forward, without the slightest sound.