"Wonderful!" exclaimed Elaine. "That was very realistic."

We brushed our way out through the thick palms, congratulating Kennedy on the perfect success of his demonstration.

So astonished were we that we did not hear the doorbell ring. Jennings answered it and admitted two men.

"Is Professor Kennedy here?" asked one. "We have been to his apartment and to the laboratory."

"I'll see," said Jennings discretely, taking the card of one of them and leaving them in the drawing-room.

"Two gentlemen to see you, Mr. Kennedy," Jennings interrupted our congratulations, handing Craig a card. "Shall I tell them you are here, sir?"

Craig glanced at the card. "I wonder what that can be?" he said, turning the card toward us.

It was engraved:

W. R. Barnes U. S. Secret Service.

"Yes, I'll see them," he said, then to us, "Please excuse me?"

Elaine, Aunt Josephine and I strolled off in the palms toward the Fifth Avenue side, while Jennings went out toward the back of the house.

"Well, gentlemen," greeted Kennedy as he met the two detectives, "what can I do for you?"

The leader looked about, then leaned over and whispered, "We've just had word, Professor, that your model of the torpedo has been stolen from the Navy Department in Washington."

"Stolen?" repeated Kennedy, staring aghast.

"Yes. We fear that an agent of a foreign government has found a traitor in the department."

Rapidly Kennedy's mind pictured what might be done with the deadly weapon in the hands of an enemy.

"And," added the Secret Service man, "we have reason to believe that this foreign agent is using a Chinaman, Wu Fang."

"But Wu has been arrested," replied Craig. "I arrested him myself. The police have him now."

"Then you don't know of his escape?"

Kennedy could only stare as they told the story.

Suddenly, down the hall, came cries of, "Help! Help!"

While Craig was showing us the torpedo, the criminal machinery which Wu had set in motion at orders from the foreign agents was working rapidly.

Outside the Dodge house, a man had shadowed us. He waited until we went in, then slunk in himself by the back way and climbed through an open window into the cellar.

Quietly he made his way up through the cellar until finally he reached the library. Listening carefully he could hear us talking in the conservatory. Stealthily he moved out of the library.

We had left the conservatory when he entered, peering through the palms. On he stole till he came to the fountain. He looked about.

There, bobbing up and down, was the model of the torpedo for which he had dared so much. He picked it up and looked at it, gloating.

The crook was about to move back toward the library, hugging the precious model close to himself when he heard Jennings coming. He started back to the conservatory. Jennings entered just in time to catch a fleeting glimpse of some one. His suspicions were roused and he followed.

The crook reached the conservatory and opened a gla.s.s window leading out into the little garden beside the house. He was about to step out when the sound of voices in the garden arrested him. Elaine, Aunt Josephine and I had gone out and Elaine was showing me a new rose which had just been sent her.

The crook fell back and dropped down behind the palms. Jennings looked about, but saw no one and stood there puzzled. Then the crook, fearing that he might be captured at any moment, looked about to see where he might hide the torpedo. There did not seem to be any place. Quickly he began to dig out the earth in one of the palm pots. He dropped the torpedo, wrapped still in the handkerchief, into the hole and covered it up.

Jennings was clearly puzzled. He had seen some one rush in, but the conservatory was apparently empty. He had just turned to go out when he saw a palm move. There was a face! He made a dive for it and in a moment both he and the crook were rolling over and over.

Kennedy and the Secret Service men were talking earnestly when they heard the cry for help and the scuffle. They rushed out and into the conservatory in time to see the crook, who had broken away, knock out Jennings. He sprang to his feet and darted away.

Kennedy's mind was working rapidly. Had the man been after the other model? The detectives went after him. But Craig went for the torpedo.

As he looked in the tank, it was gone! He turned and followed the crook.

I was still in the garden with Elaine and Aunt Josephine when I heard sounds of a struggle and a moment later a man emerged through the window of the conservatory followed by two other men. I went for him, but he managed to elude me and dashed for the wall in the back of the garden. The Secret Service men fired at him but he kept on. A moment later Craig came through the window.

"Did any of you take the torpedo?" he asked.

"No," replied Elaine, "we left it just as you had it."

Kennedy seemed wild with anxiety. "Then both models have been stolen!"

he cried, dashing after the Secret Service men with me close behind.

The crook by this time had reached the top of the wall. Just as he was about to let himself down safely on the other side, a shot struck him.

He pitched over and we ran forward.

But he had just enough of a start. In spite of the shock and the wound he managed to pick himself up and with the help of a confederate hobbled into a waiting car, which sped away just as we came over the wall.

We dropped to the ground just as another car approached. Craig commandeered it from its astonished driver, the Secret Service men and I piled in and we were off in a few seconds in hot pursuit.

Down at the terminal where trains came in from Washington, Wu, much better now, was waiting.

He had pulled a long coat over his Chinese clothes and wore a slouch hat. As he looked at the incoming pa.s.sengers he spied the man he was waiting for, the young crook who had been waiting in the shrubbery outside the Navy Building when the torpedo model was thrown out.

The man had the model carefully wrapped up, under his arm. As his eye travelled over the crowd he recognized Wu but did not betray it. He walked by and, as he pa.s.sed, hastily handed Wu the package containing the model. Wu slipped it under his coat. Then each went his way, in opposite directions.

It was a close race between the car bearing the two crooks and that which Kennedy had impressed into service, but we kept on up through the city and out across the country, into Connecticut.

Time and again they almost got away until it became a question of following tire tracks. Once we came to a cross-road and Kennedy stopped and leaped out. Deeply planted in the mud, he could see the tracks of the car ahead leading out by the left road. Close beside the tire tracks were the footprints of two men going up the right hand road toward the Sound.

"You follow the car and the driver," decided Craig, hastily indicating the road by which it had gone. "I'll follow the footprints."