trip to New York and back.
"What's that?" I asked.
"This? This is a little instrument known as the audion, a wireless electric-wave detector."
"Outside the hull?" repeated Shirley, still dazed.
"Yes," cried Kennedy excitedly. "I got my first clue from that flickering Welsbach mantle last night. Of course it flickered from the wireless we were using, but it kept on. You know in the gas-mantle there is matter in a most mobile and tenuous state, very sensitive to heat and sound vibrations.
"Now, the audion, as you see, consists of two platinum wings, parallel to the plane of a bowed filament of an incandescent light in a vacuum. It was invented by Dr. Lee DeForest to detect wireless. When the light is turned on and the little tantalum filament glows, it is ready for business.
"It can be used for all systems of wireless—singing spark, quenched spark, arc sets, telephone sets; in fact, it will detect a wireless wave from whatever source it is sent. It is so susceptible that a man with one attached to an ordinary steel-rod umbrella on a rainy night can pick up wireless messages that are being transmitted within some hundreds of miles radius."
The audion buzzed.
"There—see? Our wireless is not working. But with the audion you can see that some wireless is, and a fairly near and powerful source it is, too."
Kennedy was absorbed in watching the audion.
Suddenly he turned and faced us. He had evidently reached a conclusion. "Captain," he cried, "can you send a wireless message? Yes? Well, this is to Burke. He is over there back of the hotel on the hill with some of his men. He has one there who understands wireless, and to whom I have given another audion. Quick, before this other wireless cuts in on us again. I want others to get the message as well as Burke. Send this: 'Have your men watch the railroad station and every road to it. Surround the Stamford cottage. There is some wireless interference from that direction.'"
As Shirley, with a half-insane light in his eyes, flashed the message mechanically through space, Craig rose and signalled to the house. Under the portecochére I saw a waiting automobile, which an instant later tore up the broken-stone path and whirled around almost on two wheels near the edge of the cliff. Glowing with health and excitement, Gladys Shirley was at the wheel herself. In spite of the tenseness of the situation, I could not help stopping to admire the change in the graceful, girlish figure of the night before, which was now all lithe energy and alertness in her eager devotion to carrying out the minutest detail of Kennedy's plan to aid her father.
"Excellent, Miss Shirley," exclaimed Kennedy, "but when I asked Burke to have you keep a car in readiness, I had no idea you would drive it yourself."
"I like it," she remonstrated, as he offered to take the wheel. "Please—please—let me drive. I shall go crazy if I'm not doing something. I saw the Z99 go down. What was it? Who—"
"Captain," called Craig. "Quick—into the car. We must hurry. To the Stamford house, Miss Shirley. No one can get away from it before we arrive. It is surrounded."
Everything was quiet, apparently, about the house as our wild ride around the edge of the harbour ended under the deft guidance of Gladys Shirley. Here and there, behind a hedge or tree, I could see a lurking secret-service man. Burke joined us from behind a barn next door.
"Not a soul has gone in or out," he whispered. "There does not seem to be a sign of life there."
Craig and Burke had by this time reached the broad veranda. They did not wait to ring the bell, but carried the door down literally off its hinges. We followed closely.
A scream from the drawing-room brought us to a halt. It was Mrs. Brainard, tall, almost imperial in her loose morning gown, her dark eyes snapping fire at the sudden intrusion. I could not tell whether she had really noticed that the house was watched or was acting a part.
"What does this mean?" she demanded. "What—Gladys—you—"
"Florence—tell them—it isn't so—is it? You don't know a thing about those plans of father's that were—stolen—that night."
"Where is Nordheim?" interjected Burke quickly, a little of his "third degree" training getting the upper hand.
"Nordheim?"
"Yes—you know. Tell me. Is he here?"
"Here? Isn't it bad enough to hound him, without hounding me, too? Will you merciless detectives drive us all from place to place with your brutal suspicions?"
"Merciless?" inquired Burke, smiling with sarcasm. "Who has been hounding him?"
"You know very well what I mean," she repeated, drawing herself up to her full height and patting Gladys's hand to reassure her. "Read that message on the table."
Burke picked up a yellow telegram dated New York, two days before.
It was as I feared when I left you. The secret service must have rummaged my baggage both here and at the hotel. They have taken some very vaulable papers of mine.
"Secret service—rummage baggage?" repeated Burke, himself now in perplexity. "That is news to me. We have rummaged no trunks or bags, least of all Nordheim's. In fact, we have never been able to find them at all."
"Upstairs, Burke—the servants' quarters," interrupted Craig impatiently. "We are wasting time here."
Mrs. Brainard offered no protest. I began to think that the whole thing was indeed a surprise to her, and that she had, in fact, been reading, instead of making a studied effort to appear surprised at our intrusion.
Room after room was flung open without finding any one, until we reached the attic, which had been finished off into several rooms. One door was closed. Craig opened it cautiously. It was pitch dark in spite of the broad daylight outside. We entered gingerly.
On the floor lay two dark piles of something. My foot touched one of them. I drew back in horror at the feeling. It was the body of a man.
Kennedy struck a light, and as he bent over in its little circle of radiance, he disclosed a ghastly scene.
"Hari-kiri!" he ejaculated. "They must have got my message to Burke and have seen that the house was surrounded."
The two Japanese servants had committed suicide.
"Wh-what does it all mean?" gasped Mrs. Brainard, who had followed us upstairs with Gladys.
Burke's lip curled slightly and he was about to speak.
"It means," hastened Kennedy, "that you have been double crossed, Mrs. Brainard. Nordheim stole those plans of Captain Shirley's submarine for his Titan Iron Works. Then the Japs stole them from his baggage at the hotel. He thought the secret service had them. The Japs waited here just long enough to try the plans against the Z99 herself—to destroy Captain Shirley's work by his own method of destruction. It was clever, clever. It would make his labours seem like a failure and would discourage others from keeping up the experiments. They had planned to steal a march on the world. Every time the Z99 was out they worked up here with their improvised wireless until they found the wave-length Shirley was using. It took fifteen or twenty minutes, but they managed, finally, to interfere so that they sent the submarine to the bottom of the harbour. Instead of being the criminal, Burke, Mrs. Brainard is the victim, the victim both of Nordheim and of her servants."
Craig had thrown open a window and had dropped down on his knees before a little stove by which the room was heated. He was poking eagerly in a pile of charred paper and linen.
"Shirley," he cried, "your secret is safe, even though the duplicate plans were stolen. There will be no more interference."
The Captain seized Craig by both hands and wrung them like the handle of a pump.
"Oh, thank you—thank you—thank you," cried Gladys, running up and almost dancing with joy at the change in her father. "I—I could almost—kiss you!"
"I could let you," twinkled Craig, promptly, as she blushed deeply.