"Send for him, Professor," urged his accomplice. "Those Englishmen are getting too close to be pleasant. The British army of occupation will be carrying out a thorough search of the Schwarzwald if these men get away, and then where shall we be?" "We are in the neutral zone, though," replied the other. "But we’re contravening the Peace Regulations, sir, and the English will not stand upon ceremony. It will be too late should these men get away." "Donner und Teufel!" rasped out the angry professor. "Don’t speak to me of the Peace Regulations. There will be no peace till Germany regains all and more than all she has lost. I will send for this Commissioner of Aerial Police, for I believe that he and his two accomplices, Keane and Sharpe, are the only ones so far who know anything that matters about the secret of the Schwarzwald," and he began to tap the keys, reeling out the words as he sent them. Keane listened acutely for the cyphers of the code. They were:-- "Z--X--B--T--V--O--P..." and he understood that Tempest was to come at once, make for Mulhausen aerodrome, then take a bee-line, east-north-east over the Schwarzwald until he saw a smoke column, where a suitable landing-ground would be found, and his accomplices would await him. "Ach!" shrieked the professor, with a fiendish laugh. "The smoke column will mark his last resting-place. They shall all be buried together, these mad Englishmen. We will have more live wires stretched across his landing-ground, and as the wild boar died, so will these men die who dared to follow me into the Schwarzwald." "The wild boar! Hoch! Hoch!" exclaimed his companion. "It is a fitting tribute for the English are swine!" "And the _Scorpion_ shall witness the inglorious end of these men," cried the professor, as a sudden idea came into his mind. "Der _Scorpion_?" queried Fritz, looking up amazed from his task. "What do you mean, Professor?" "Why, the Rittmeister will have finished his work in the Hamadian Desert this afternoon. His instructions are to resign the Sultanate of those regions for the present, for the skies will be thick with British scouts by to-morrow." "But then he goes to Ireland to work with the revolutionists there, does he not, mein herr?" "Ja! ja! but I will ask him to call here for a day or two before he proceeds. He will have much to tell us, and Spitzer, Carl and Max would like to see these dangerous opponents safely out of the way, for at present they are the only enemies to be considered." "Gut!" ejaculated Strauss, catching something of the professor’s enthusiasm. Keane would have intervened before this, for he had noted Sharpe’s impatience, but he intimated as well as he could by mute signs and otherwise, that the fiend was doing their work for them. "Let him send this message first," he whispered in his companion’s ears, "and then----" But the sentence was completed by further cabalistic signs.