The man Bohlen, seeing his companion come out, moved away from the gate across the lawn back to the house, whereupon Kennedy crept up to the spot where the German had been standing, and whence they could obtain a good view of the shed from which the dastardly attempt was to be made. Beside the gate they found a walking-stick--a thick one made of bamboo. "That fellow has forgotten his stick," remarked Kennedy, taking it up, all unconscious of the peril. From one of the darkened windows of the house Ortmann was watching his action, and chuckled. Of a sudden, however, a fierce blood-red flash lit up the whole country-side, and with a deafening roar, the shed was hurled high into the air, together with the shattered remains of the man who had pressed the key. Instead of exploding the mine under the railway tunnel, as was intended, he had exploded the tinful of picric acid derivative which Kennedy had concealed beneath the straw! Then, a few seconds later, the heavy train laden with munitions for the British front emerged from the tunnel in safety, its driver all unconscious of the desperate attempt that had been made by the enemy in our midst. Kennedy, having witnessed the consummation of his well-laid plan to blow up any conspirator who touched the key, cast the walking-stick to the ground and, taking Ella's arm, retraced his steps through the woods. But they had not gone far ere a second explosion, a sharp concussion which they felt about them, came from somewhere behind them. "Funny!" he remarked to his well-beloved. "I wonder what that second noise was, dearest?" "I wonder," said Ella, and they both hurried back to their car. CHAPTER THREE. THE HYDE PARK PLOT. Two men sat in a big, handsome dining-room in one of the finest houses in Park Lane. One was Theodore Drost, dressed in his usual garb of a Dutch pastor. A look of satisfaction overspread his features as he raised his glass of choice Chateau Larose. Opposite him at the well-laid luncheon table sat his friend, Ernst Ortmann, alias Horton, alias Harberton, the super-spy whose hand was--if the truth be told--"The Hidden Hand" upon which the newspapers were ever commenting--that secret and subtle influence of Germany in our midst in war-time. Count Ernst von Ortmann was a very shrewd and elusive person. For a number of years he had been a trusted official in the entourage of the Kaiser, and having lived his early life in England, being educated at Oxford, he was now entrusted with the delicate task of directing the advance guard of the German army in this country.