Next morning at nine o'clock I was seated on the side of his bed, telling him of the incident of the lamp.

"Ah!" he exclaimed after a pause. "My surmises are slowly proving correct, Jack. You must buy a bicycle-lamp down in the town and a piece of green glass. To-night you must go there at the same hour and show a similar light. The matter seems far more serious than I first expected. The enemy is no doubt here, in our midst. Take this. It may be handy before long," and he took from his kit-bag a new .32 Colt revolver.

By this, I saw that he had resolved upon some bold stroke.

That evening, after an early dinner at the hotel, we took train to North Queensferry, and on alighting at the station he sent me up to the golf-links to show a light for half an hour; promising to meet me later at a certain point on the road to Rosyth.

I gained the lonely spot on the golf-course and duly showed the light. Then I hastened to rejoin my friend at the point he indicated, and found him awaiting me behind some bushes.

Almost at the moment we met, a female figure came along beneath the shadow of a high wall. She was a poorly dressed girl, but the instant she addressed my friend I recognised by her refined voice that it was Vera, the dainty daughter of the Admiral Superintendent.

"Elsie is waiting down by the Ferry Barns," she said quickly, in a low whisper, after greeting me. "Heinrich has not kept his appointment with her."

"You have the note?" he asked. "Recollect what I told you concerning the man Hartmann."

"Yes," she replied. Then, addressing me, she said, "Take care of these people Mr. Jacox. They are utterly unscrupulous"; and she again disappeared into the darkness.

Ray and I turned and again walked back in the direction of Rosyth. But when we had gone a little distance he told me to approach the naval offices carefully, conceal myself in the bushes, and watch until he joined me. On no account was I to make any sign, whatever I might witness.

Though intensely cold the night was not very dark, therefore I was not long in establishing my position at a spot where I had a good view of the offices. Then I leaned upon a tree-trunk and waited in breathless expectation. I touched my father's old repeater which I carried and found it to be a quarter past midnight.

For over an hour I remained there, scarce daring to move a muscle.

Suddenly, however, upon the mud at the side of the road I heard soft footsteps, and a few moments later two figures loomed up from the shadow. But when about forty yards from the offices they halted, one of the men alone proceeding.

With great caution he climbed the spiked railing, and crossing rapidly to the main door of the offices he unlocked it with a key and entered, closing the door after him. As far as I could distinguish, the man wore a short beard, and was dressed in tweeds and a golf cap. Holding my breath, I saw the flashing of an electric torch within the building.

Fully twenty minutes elapsed before he reappeared, relocked the outside door, and clambering back over the railings, rejoined his waiting companion, both being lost next second in the darkness.

I longed to follow them, but Ray's instructions had been explicit – I was to wait until he arrived.

Half an hour later, hearing his low whistle, I emerged from my hiding-place to meet him and tell him what I had seen.

"Yes," he said, "I know. We have now no time to lose."

And together we hurried back over the road towards North Queensferry.

At the same spot where Vera had met us, we found her still in hiding. My friend whispered some words, whereupon she hurried on before us to the sharp bend in the road where stood the telegraph-pole which had attracted Ray on the night of our first arrival.

We drew back in the shadow, and as we did so I saw her halt and pull the bell beside a small gate in a high wall. Behind stood a white-washed cottage, with a good-sized garden at the rear. One end of the house abutted upon the pathway, and in it was one small window commanding a view of the road.

Vera, we saw, had some conversation with the old woman who answered her ring, and then went in, the gate being closed after her.

Together we waited for a considerable time, our impatience and apprehension increasing. All was silent, except for a dog-cart, in which we recognised Mr. Wilkinson driving home from the station.

"Curious that Vera doesn't return," Ray remarked at last, when we had waited nearly three-quarters of an hour. "We must investigate for ourselves. I hope nothing has happened to her."

And motioning me to follow, he very cautiously crept along the muddy path and tried the gate. It had been relocked.

We therefore scaled the wall without further ado, and, standing in the little front garden, we listened breathlessly at the door of the house.

"Get back there in the shadow, Jack," urged my friend; and, as soon as I was concealed, he passed his hand along the lintel of the door, where he found the bell-wire from the gate. This he pulled.

A few moments later the old woman reappeared at the door, passing out towards the gate, when, in an instant, Ray and I were within, and flinging open a door on the left of the narrow passage we found ourselves confronted by the exemplary waiter Klauber and a companion, whose short beard and snub nose I recognised as those of the man who so calmly entered the naval offices a couple of hours before.

For them our sudden appearance was, no doubt, a dramatic surprise.

The elder man gave vent to a quick imprecation in German, while Klauber, of course, recognised us both.

In the room was a large camera with a flashlight apparatus, while pinned upon a screen before the camera was a big tracing of a plan of one of the chief defensive forts which the spies had that night secured from Rosyth, and which they were now in the act of photographing.

"A lady called upon you here an hour ago," exclaimed Ray. "Where is she?"

"No lady has called here," replied the bearded German in very good English, adding with marvellous coolness, "To what, pray, do we owe this unwarrantable intrusion?"

"To the fact that I recognise you as Josef Scholtz, secret agent of the German Naval Intelligence Department," answered my friend resolutely, closing the door and standing with his back to it. "We have met before. You were coming down the steps of a house in Pont Street, London, where lives a great friend of yours, Hermann Hartmann."

"Well?" asked the German, with feigned unconcern, and before we could prevent him he had torn the tracing from the screen, roughly folded it, and stuffed it into his pocket.

"Hand that to me," commanded my friend quickly.

But the spy only laughed in open defiance.

"You intended, no doubt, to replace that as you have done the others after photographing them. Only we've just spoilt your game," Raymond said. "Both Mr. Wilkinson and Mr. Farrar are, I see from the list, members of the Golf Club where you" – and he looked across to the waiter – "are employed. On one occasion, while Mr. Wilkinson was taking a bath after a game, and on another while Mr. Farrar was changing his coat and vest, you contrived to take wax impressions of both the safe keys and also that of the door of the offices. The keys were made in Glasgow, and by their means the plans of our new naval base and its proposed defences have been at your disposal."

"Well – there's no law against it!" cried Scholtz. "Let me pass."

"First give me that tracing," demanded my friend resolutely.

"Never. Do your worst!" the German replied, speaking with a more pronounced accent in his excitement, while at the same moment I saw that he held a revolver in his hand.

In an instant Ray drew his own weapon, but, instead of covering the spy, he pointed it at a small, strong wooden box upon the floor in the opposite corner of the room.

"Gott – no!" gasped the man, his face blanching as he realised Ray's intention. "For Heaven's sake don't. I – I – "

"Ah!" laughed my friend. "So it is as I thought. You two blackguards, with some of your friends, I expect, have been secretly preparing for the destruction of the Forth Bridge on 'the Day' – as you are so fond of calling it. The staples are already driven in, and the unsuspicious-looking wire ropes, attached to which the boxes of gun-cotton and other explosives are to be sunk between the four caissons, are all in readiness. The boat from a German merchant vessel off Leith, signalled at intervals by your assistant Klauber, has been bringing up box after box of that dangerous stuff and landing it at the bottom of this garden; so that within an hour of receiving the code-word from your chief, you would be able to wreck the whole bridge and blow it into the water!"

The spy endeavoured to pass, but seeing Ray's determined attitude, held back, and my friend compelled him to lay down his weapon.

"Jack," said my friend, "just see what's in that box."

I at once investigated it, and discovered within only innocent-looking tin boxes of English biscuits. The three tins at the top I lifted out and placed on the floor, but those below I found were filled with circular cakes of what looked like felt, about an inch in thickness, each with a hole through it, and with a small cavity for the reception of the detonator. I showed it to Ray, pointing out that, packed with it, were several smaller tins, like boxes of cigarettes.

"Yes. I see!" he exclaimed as I opened one. "Those are the detonators, filled with fulminate of mercury."

"Let us pass!" cried both the spies.

"Not before you are searched shall you leave this house!" was the quick reply. "If you resist, I shall fire into one of those boxes of detonators, and blow you to atoms."

"And yourselves also!" remarked Klauber, his face pale as death.

"It will at least prevent our secrets falling into your hands, and at the same time bring the truth home to the British Government!" was my friend's unwavering answer.

Next moment both men made a dash towards the door, but I had drawn my weapon and was upon my guard. There was a flash, followed by a deafening report, as Ray fired at the box, aiming wide on purpose.

Then the two spies, seeing that they had to deal with a man who was a patriot to his heart's core, realised that their game was up.

Sullenly Scholtz put down his weapon, and I searched both men.

From the pocket of the exemplary waiter I drew forth a rough plan, together with some scribbled notes in German, which afterwards proved to be a description of the forts on Inchkeith, while from the pocket of Scholtz I secured the tracing he had stolen from Rosyth.

Then we allowed both the secret agents of the Kaiser to pass out, much to the consternation and alarm of the deaf old Scotchwoman, who had, at their request, posed as the occupier of the cottage, but who, in perfect ignorance of what was in progress, had acted as their housekeeper.

A swift examination of the premises revealed no trace of Vera. But we found in the cellar below the room where we had found the spies a great store of gun-cotton and other high explosives of German manufacture, intended for the wrecking of the bridge; while in an old battered portmanteau in one of the upstairs rooms we also found, all ready for conveyance to Germany, a quantity of prints from the photographic negatives in the room below – photographs of nearly the whole of the plans of Rosyth, and more especially of its proposed forts – which the men had been in the habit of abstracting at night and replacing in the safe before dawn.

Ray Raymond was in active search of something else besides, and at length discovered what he sought – two German military telegraph instruments, together with a complete and very ingenious arrangement for the tapping of wire.

"By Jove!" exclaimed my friend, who took a keen interest in all things electrical. "This will now come in very handy!"

And on going outside to the telegraph pole against the wall, he clambered up it and attached wires to two of the insulators. Then descending, he screwed a little brass box upon it into those same three holes in the black wood which had attracted him on the night of our arrival, and a moment later began manipulating the key.

"Good!" he exclaimed at last. "I've picked up Inverkeithing, and asked them to send the police over at once. We mustn't leave the place and risk the spies returning for any of their paraphernalia. The disappearance of Vera, however, worries me. I sent her here with a note purporting to come from the chief of the German Secret Service in England, Hermann Hartmann; but she has vanished, and we must, as soon as the police arrive, go in search of her."

So completely had we unmasked the spies that I stood puzzled and amazed.

Ray, noticing my attitude, made explanation.

"Several of my surmises in this case proved entirely correct," he said. "My first suspicion was aroused that if spies were about, they would probably prepare for tapping the telegraph lines, and, as you know, I soon discovered evidence of it. Then those staples in the foundations of the bridge gave me a further clue to the work in progress, a suspicion greatly strengthened by the signal light shown by the man Klauber. The two men who held the safe keys being members of the Golf Club aroused a theory which proved the correct one, and on tracing back the career of the waiter I made a remarkable discovery which left no doubt as to his real profession. It seems that while employed at the Café de l'Europe in London, he lodged at the house of Mrs. Jephson, in Shepherd's Bush, and became extremely friendly with the widow's son. Now you'll remember that a few days before the poor fellow's death he was absent mysteriously, and on his return he told his mother in confidence that there would shortly be something in the papers about himself. Well, the truth is now quite plain. During his absence he evidently came up here. Young Jephson, who knew German, had found out that his German friend was a spy, and had no doubt secured the document afterwards found upon him as evidence. Klauber was ignorant of this, though he suspected that his secret was out. In deadly fear of exposure, he then plotted to silence the young Englishman, inducing him to walk along the towing-path between Hammersmith and Barnes, where he no doubt pushed him into the river. Indeed, I have found a witness who saw the two men together in King Street, Hammersmith, on the evening of the poor fellow's disappearance. The plan which Reitmeyer saw is, I find, fortunately one of the discarded ones."

"Extraordinary!" I declared, absorbed by what he had related. "But while you've wrested from Germany the secrets of some of our most important defences, you have, my dear Ray, temporarily lost the woman you love!"

"My first duty, Jack, is to my King and my country," he declared, sitting on the edge of the table in the spies' photographic studio. "I have tried to perform it to-night, and have, fortunately, exposed the German activity in our midst. When the police arrive to view this spies' nest, we must at once search for her who is always my confidante, and to whose woman's wits and foresight this success is in no small measure due."