Just as the liner turned the submarine broke water--why, I never could understand. Probably her commander was too supremely certain that his shot had gone home, or else some error in navigation had brought him to the surface earlier than he intended, for obviously it was his duty to remain submerged until he was sure his work was done. Be that as it may, it was his last mistake. As the grey whale-back of the submarine rose above the water the gun of the _Athabasca_ spoke. The first shot was over, the second short. Before the third was fired we had also bobbed up suddenly, and the U-boat found herself the target of two antagonists. There could be only one end to such a fight. Almost simultaneously the third shot of the _Athabasca_ and our first rang out, and both shells found their mark. One struck the conning-tower fair and square, blowing it clean away; the other crashed into the upper part of the hull, tearing a huge gap, and in a few seconds the enemy vessel had sunk with all hands, leaving only a flood of oil on the heaving surface of the sea to show where she had disappeared. Next day I was on the Sud Express for Paris, while Madame Gabrielle, whom I had recalled by wire, followed me a few hours later. From Hecq in Paris I learned the full sequel of our adventure. No news of the affair ever leaked out to the public. But it appears that, owing to the discovery of the plans from Kiel in possession of the submarine's captain and our wireless messages, French destroyers and British submarines, operating together, had within twelve hours cleaned out the pirates' nest, sinking four more submarines and taking nearly sixty prisoners, most of whom are now behind barbed wire in Wales. CHAPTER FOUR. THE HIDDEN HAND IN BRITAIN. "Ah! my dear Hecq--you have now set me a very difficult task--very difficult indeed!" I found myself saying a few weeks later, after I had mastered, with a good deal of trouble, a formidable dossier which had been laid before me by the astute chief of the French Secret Service, now promoted, by the way, to be chief of the International Secret Service Bureau of the Allies. Though the time had been short since my return from Spain, much had happened. At length "unity of command" in contra-espionage work had been realised as an absolute essential for securing a definite mastery over the incessant plottings of the Huns, and, with the cordial goodwill of all, Armand Hecq--whose brilliant abilities had given him a commanding position--had been unanimously chosen for the much coveted post. "I admit it is extremely difficult," said the short, grey-bearded, alert little man, knocking the ash from his excellent cigar, leaning back in his cane deck-chair, and regarding me with an amused smile. "It is so difficult that I confess I do not see my way at all clearly. For that reason I have put the matter before you."