Having thus secured his opponent, Ramblethorne watched the result of the encounter between his fellow-spy and young Haye.
Von Ruhle had opened the attack by brandishing his heavy stick, and calling upon Vernon to surrender.
Haye returned the compliment by closing, and dealing the German such a terrific blow upon the chest that von Ruhle recoiled quite a couple of yards. The lad's onslaught had only missed the German's solar plexus by a few inches; had it not, the chances were that von Ruhle would have lost all interest in life for the next quarter of an hour.
But instead of following up his initial success Vernon, seeing Ross helpless in the doctor's grip, rushed to his chum's aid. For a few seconds he feinted, striving to find an opening, while Ramblethorne, dragging his captive with him, pivoted in order to keep his front towards his new antagonist.
Those few seconds were Vernon's undoing.
Quickly recovering himself, von Ruhle sprang forward with the agility of a panther. The imitation Malacca cane descended with a dull thud upon the lad's head, and like a felled ox Vernon fell inertly upon the sodden grass.
"Hold him—so," exclaimed Ramblethorne, handing Ross over to the custody of von Ruhle. Then drawing a small hypodermic syringe from a case, the former inserted the needle into the lad's forearm.
Five seconds later Ross Trefusis lay unconscious beside his companion in misfortune.
CHAPTER III. Kidnapped
"I thought you had killed him, von Ruhle," said the doctor, bending over Vernon and making a cursory examination of the unconscious lad.
"I thought I had," was the unconcerned reply. "Dead men tell no tales."
"There I beg to differ," protested Ramblethorne. "Corpses have a nasty way of turning up at inopportune moments. These youngsters are worth more to us alive than dead."
"How so?"
"One is a son of Admiral Trefusis; his companion is, I believe, also a son of a distinguished English naval officer."
"Well, and what of it?" asked von Ruhle.
"Hostages," replied the doctor briefly. "Later I will explain. Meanwhile we'll carry them to the cave. It's farther than back to the ruins; but perhaps, as young Trefusis said, there may be a search-party, and the ruins would be one of the first objects of investigation."
Although, with the exception of periodical visits abroad, Dr. Ramblethorne had lived in England all his life and was a fully qualified medical man, he was a highly trusted and talented agent of the German Secret Service. Months before the outbreak of war, he had been ordered to report upon the defences of Devonport, and in order to do this he had bought a practice on the outskirts of Plymouth. Upon the commencement of hostilities, he was detailed to keep under observation the military preparations of the Duchy of Cornwall, and also to take necessary steps for communicating with German submarines that, under von Tirpitz's prearranged scheme, were to operate in the Bristol Channel. Von Ruhle was one of the few subordinates he actually knew. There were others with whom he communicated only through an intermediary, and who knew him only by a number.
Von Ruhle was almost as mentally clever as his superior. Ostentatiously he was an Englishman. Sometimes he posed as a mining engineer; at others as a commercial traveller; as an accredited representative of the British Red Cross Society he was in the habit of making frequent journeys to Holland, presumably in connection with work at Groningen Internment Camp. At the present time, his activities were centred upon the formation of a secret petrol depot for the supply of fuel to unterseebooten operating in the Bristol Channel and off the south coast of Ireland.
A couple of slight incidents had served to put the cautious Ramblethorne on his guard during his interview with von Ruhle in the ruined chapel.
Although he verbally deprecated his subordinate's alarm when the lads accidentally dislodged a stone from the tower, it was merely to disarm possible eavesdroppers of any suspicion that their presence was suspected.
The ability to control his feelings was one of the super-spy's chief assets. Suspicion once aroused, he proceeded without the faintest sign to investigate his surroundings. His keen eye soon lighted upon the lads' sweaters. Then it was that an adjournment was suggested to Main Beach Cove.
This was simply and solely a "blind", for on gaining the cover of the boulder-strewn hillock the doctor communicated his suspicions to his companion. The pair then crouched behind the rocks, whence they were able to command a view of the tower.
It was not long before their enterprise met with success. They saw Trefusis and his chum cautiously descend by means of the ivy; then, directly the lads set out upon their ill-starred tracking expedition, the Germans, as before related, succeeded in outflanking them and effecting their capture.
"Time!" announced Ramblethorne, consulting his watch.
"Are these safe?" asked von Ruhle, stirring Vernon's unconscious form with his foot.
"Quite; though, perhaps, to make sure I will give this youngster a slight injection. Pity you hadn't held him with the double arm-lock instead of cracking him over the head. Herr Kapitan Schwalbe won't want to be troubled with a passenger with a swollen head."
Leaving their senseless victims in the cave, the two Germans again ascended the hill to St. Mena's Chapel. As they breasted the summit, they could see the fixed white light of Black Bull Head showing momentarily brighter and brighter against the rapidly failing daylight.
Setting a prismatic compass in position upon the sill of one of the glazeless windows, Ramblethorne took a careful bearing in a seaward direction. This done, he pointed the projector of the signalling apparatus in precisely the same direction, and threw a waterproofed cloth over the instrument.
"Too early yet, von Ruhle," he remarked. "Nevertheless it is advisable to fix our bearings while twilight lasts. A light might spell disaster."
"A deucedly unpleasant night for such a task," grumbled von Ruhle.
"On the contrary, it is just the very thing," replied the doctor. "It is not thick enough to be dangerous, but the rain is just sufficient to assist in the screening of U75. Do not think of your personal comfort, my dear von Ruhle, when urgent work for the Fatherland has to be undertaken."
For another half-hour the two men paced the grass-grown stones. Their choice of St. Mena's Island as a secret signalling station was an excellent one. It was isolated, and, being slightly greater in elevation than the cliffs of the mainland in the immediate vicinity, would effectually screen any ray of light sent landwards from the expected German submarine. Thus all danger of the narrow gleam of reflected light being detected by the none too smart members of the coast patrol was entirely obviated.
"Time!" exclaimed the doctor, consulting the luminous face of his watch.
Dexterously, and without disturbing the position of the instrument, von Ruhle whipped off the covering. Although there were no visible signs that anything was taking place, both men knew that a beam of light, reflected from the distant lighthouse on Black Bull Head, was being directed seawards.
In silence the two men peered through the driving rain, von Ruhle making use of a pair of powerful night-glasses.
Suddenly, after an interval of almost five minutes, a faint pin-prick of light flickered from the surface of the sea.
Instantly Ramblethorne stepped a dozen paces to the right.
"I can see nothing from here," he announced in a low voice. "Can you?"
"Yes," replied his companion.
"Good: that's friend Schwalbe."
The doctor was right. From the deck of the unterseeboot a signalling apparatus similar to that employed by the spies was in use. By an ingenious automatic arrangement it projected a beam of light, derived from the same sources as that on St. Mena's Island, rigidly in a fixed direction, regardless of the "lift" of the submarine under the action of the waves.