The next moment the professor was busy at the wireless keys, transmitting some message to the far deserts of Arabia. "By all the saints," gasped Keane, "he’s sending a message to the raider, the _Scorpion_, as he calls it. I must have that secret code at all hazards. I wonder what he is saying?" For some time the chief conspirator was engaged coding and decoding messages at the little table where the aerials, carefully hidden amongst the trees without, had their terminus. And in that moment Keane thanked his stars that he had waited for this, for he saw new possibilities opening out before him. Once in possession of this mechanism and the necessary codes, he could communicate at will with the distant raider, who was threatening the whole civilised world by his almost superhuman powers of brigandage. He could recall the raider also, and make his capture certain, once he could secure absolute possession of this little citadel. For the present he could do nothing but wait, however, and see how matters developed. Once, the assistant came quite close to their hiding-place, and both men again gripped their Webleys. At this moment even to breathe seemed fraught with danger. If the man should enter the little apartment, he must die, and the professor must be immediately threatened with the same penalty unless he surrendered. "Ha! So far so good!" gasped Keane, as the mechanic recrossed the workshop without actually entering their hiding-place. "Teufel!" spluttered the professor. "Here is that fool Tempest trying to communicate with those two _verdammt_ Englishmen who are still roaming about in the Schwarzwald. He little knows that we possess his secret code." "Himmel! What does he say?" asked the other. "Wants them to report progress at once, and let him know how matters stand," said Weissmann in a mocking tone. "He says he will come over himself, if necessary." "Donnerwetter! Ask him to come, Professor. He might as well grill with his accomplices on the live wires, for that’s where they’ll be before the day is out, unless they abandon their futile search," replied Strauss. "This fiend is a perfect wizard!" thought Keane, and his glance signified as much to Sharpe. "How he manages to get hold of these secrets is beyond me. And yet, there is a defect in his mad science, for he does not know that we’re here, and that his own life is in our hands. Fool that he is, he will soon learn that the wit of an Englishman is more than a match for his boasted knowledge," and here the senior airman carefully withdrew a cartridge from his Webley and inserted another, silently--a cartridge that had a specific mission. His companion watched him and repeated the action with his own weapon, for he understood. "Blitz! but I’ve half a mind to send for Tempest," mused the professor, who was still toying with the keys of the wireless instrument.