On this day of all days dignitaries from Washington must appear to inspect the aeroplane accomplishments of the Waite Motor Company. Potter chafed and treated himself to a scorching remark or two, but there was nothing for it but to give them his attention. It meant only delay. No suspicions were aroused and little was to be risked by putting off action for a few hours. But Potter was not one who liked to procrastinate; if he erred, it was toward the other extreme.... At noon he was able to turn the dignitaries over to his father.

With the return of the men to work after their dinner-hour he called his secretary.

“Have a machinist named Harker sent to me. Then find Downs, and bring him here yourself.”

The young man went out, and Potter waited with rising impatience and not without excitement. Angling for spies is a pastime likely to stir the blood.

In fifteen minutes Downs appeared, but not Harker.

“Where’s that man?” Potter demanded.

“I’ll see again, Mr. Waite,” said the secretary. He returned presently to say that the foreman had told Harker to report to Potter, that the man had left his machine to do so, and was not now to be found.

“Find that man,” Potter said, sharply.

“What do you want of me?” Downs asked, when the secretary hastened out to carry Potter’s orders.

“I’ve found the man who bosses the German agents in this plant!”

“This Harker?”

“Yes.”

“And you sent a messenger to tell him to report to you?”

“Yes.”

“Mr. Waite, you’re some manufacturer. I’ll admit that, but you’re a hell of a detective.”

“I don’t get you.”

“You might as well have sent him a card saying, ‘I suspect you—Skedaddle.’”

“You think he’s taken fright?”

“I know it.... Your telephone.”

Downs called a number. “Look up the address in your records of a man named Harker,” he said into the receiver. “We want him. He just left the plant here.... Get him.”

He turned to Potter. “Now,” he said, “suppose you let me in on this. It’s rather in my line of work, you know.”

“I suppose I should have come to you at once—but I didn’t. Here’s what I’ve got.... I have reason to suspect that a man named William Cantor is the chief of the German agents in this section. I believe his real name is Adolf von Arnheim, and he is an officer in the German army—an aviator. One of his paymasters is a chauffeur named Philip who works for Herman von Essen. Last night I saw this Philip turn over funds to Harker and another man. There you are.”

“Good work. No time to ask how you got it. Where does this Cantor hang out?”

Potter gave the address of Cantor’s office. “I never did know what his business was.”

“Can we have a car—quick?”

“Come on.”

They hastened out of the main building and to the garage where the company’s officials kept their cars. Potter’s runabout was there. “Pile in,” he said. “Where to?”

“Cantor’s office.”

Potter shot out of the archway and whirled down-town through the clear, chilly December air. He did not stop for corners or traffic officers, but, keeping his knee against the horn button, gave the car all he could give it—and Downs clung to his seat and prayed.

They drew up abruptly before the entrance to the building where Cantor maintained an office, and sprang out. The elevator carried them to the seventh floor.

“The thing is to get in without scaring whoever is there,” said Downs. “In this case the papers filed there are as valuable, more valuable, than the men. We must give them no time to destroy anything.”

Good fortune was with them. As they approached Cantor’s door a man opened it and was about to step into the corridor. Downs stepped forward quickly.

“I beg your pardon,” he said, “but can you tell me where James W. Rogers’s office is?”

The man stood with the door half opened behind him. “I’m sorry,” he said, “but I never heard the name.”

By that time Downs was within arm’s reach. He lunged forward, gripped the man, and hurled him backward through the door. Potter leaped after them.

“Shut the door!” snapped Downs from a victor’s perch on the astounded man’s chest. “Help roll him over.” The man was turned on his face and steel circles clinked upon his wrists.

“Who are you?... What does this mean?” the man said, furiously.

“I’m not sure,” said Downs, “till we take a look-see. Maybe it’s just an outrage on a respectable business man. If it is you may expect profuse apologies.”

A huge safe stood open invitingly. Downs pounced upon it, found it full of little drawers, and the drawers laden with papers, with card indices and the like—and all covered with German script. “Um!...” he said. “Read German?”

“Yes,” said Potter.

“I don’t. Talk it, but don’t read to speak of. Have a look.”

Potter unfolded a document, read it, shrugged his shoulders.

“No apologies needed,” he said to the handcuffed man. “These,” he said to Downs, “seem to be reports from agents—reports of their movements.” He examined a card from an adjoining drawer. “These are the agents, all neatly indexed, with the salaries paid,” he said. “The Germans are a systematic and efficient people.”

“They will stick to system,” said Downs, with a chuckle. “It’s a great labor-saver for us.”

“When you find the system,” said Potter, with a chuckle.

“We seem to have the whole bag of tricks. The next thing is to go over this mass of stuff and then have a general round-up.”

“Somebody will be calling here, or coming in—and give the alarm,” said Potter.

“Anybody who sticks his nose in here leaves it here,” Downs snapped.

Suddenly the man lunged forward toward the wall; seemed bent upon butting his head against it, upon grinding his face against it. Potter leaped upon him and hurled him away from the spot.... On the wall was an ordinary electric push-button such as is used to ring a door-bell. What the man had done was evident. His hands had been manacled behind him and were useless. He had pressed the button with his face.

“Where does that alarm sound?” Downs demanded.

“Find out,” said the man, sullenly.

“Some efficiency there,” said Potter, ruefully. “Of course that button was put there for just this emergency—to give the alarm if anything happened here.”

“Some other office in this building,” said Downs. “On a lower floor. That sort of arrangement wouldn’t extend outside this building. Most likely the office directly below this.... I can’t leave this room and this man. You make tracks.”

Potter rushed out of the door and down the stairs, which were close at hand, by good fortune. As his feet touched the sixth floor he saw Philip, the chauffeur, step into an elevator, heard the elevator door crash shut. He shouted, but it did not stop. The alarm had reached Philip and Philip was off to spread the warning.

Another elevator was descending. It stopped on Potter’s signal, and he stepped in. “To the ground floor—quick. Make no stops. Drop her.”

The startled elevator conductor obeyed, flung open the door as he arrived level with the street, and Potter rushed out. He reached the sidewalk just in time to see Philip in an automobile, half a block away. Potter stepped quickly into his own machine and followed. He had no other thought but to overtake Philip. Just what he should do when he overtook him was not a consideration for that moment. Headlong as usual, he counted no costs and let each second care for that second’s concerns. That he had no authority to apprehend Philip did not trouble him in the least. He believed he had the physical ability, and that was all he required.

Philip turned east at the Campus and traversed Cadillac Square to the County building and the intersection of Congress Street. Out this frayed and shabby thoroughfare he continued, not with the speed of one who fancies himself pursued, but as one travels who is upon important errand. Potter maintained a position a hundred feet behind and waited for Philip to stop.

Philip did not stop for a dozen blocks. Then he drew up at the curb before a dingy frame structure housing one of those hand-to-mouth saloons which seem to abound in Detroit, saloons which sell enormous glasses of beer for a nickel, and find difficulty to make both ends meet, to provide food for the family and funds to pay the considerable government license. Into this place Philip hastened.

Potter was at his heels, stepping into a murky room reeking with the odor of stale beer, villainous tobacco, and even more distressing aromas of cookery not guiltless of the taint of garlic. Three men occupied the barroom, the bartender, sprawling over his greasy bar, a stout man dozing in a corner, and Philip.

Upon Potter’s entrance Philip turned and faced the door, and Potter saw surprised recognition in his eyes.

“Well, Philip,” said Potter, “I’ve got you.”

“You have, eh?” said Philip. “What do you mean—got me?”

“When your friend in Cantor’s office pushed the button,” said Potter, “I tagged along after you.” He continued to advance.

“That’s far enough,” Philip said, crouching. “You tagged along, eh? Well, just tag out of that door again.”

“Better come along without a row.”

“If you want to keep your health,” said Philip, crouching, “you’ll beat it and leave me alone.”

Potter turned to the bartender, who no longer sprawled, but eyed him intently.

“This man is a German spy—trying to escape and warn other spies,” Potter said.

“No!” said the bartender, with profound astonishment. “You don’t tell me! Him? Why, I know him! He hain’t no spy—he’s a chauffeur.... You hain’t no spy, be you, Phil?”

“Certainly not. This guy is nutty.... Look here, Mr. Waite, I don’t want you should get hurt. Take your foot in your hand.”

“Are you coming with me?” Potter asked, sharply.

“Not on a Friday. Fridays is unlucky days.” He did not take his eyes off Potter’s face, but stood with a pugilist’s crouch, waiting. Potter sprang toward him, took Philip’s blow upon the side of the head, and closed in. They grappled, whirled about, trampling the floor until the glasses behind the bar danced upon the shelves. Potter was larger, stronger. He succeeded in lifting Philip from his feet and hurling him to the floor, but Philip clung to him, forcing him to sprawl on top of his prisoner. In a moment of fierce energy Potter was kneeling upon Philip’s arms and sitting upon his chest.

The stout man who had dozed in the corner shuffled to his feet and approached leisurely.

“This man is a spy. Help me tie him,” Potter panted.

“For sure,” said the man, stepping behind Potter. Then Potter felt something hard jammed against his ribs. He did not see it, nor could he feel its shape, but he knew what it was.

“What are you doing?” he said.

“Vell,” said the stout man, “I t’ink I should take some interest. I t’ink maybe it iss best if you git up und leave the young man alone. For sure. You should get up, und you should shut up. Right off.”

The man’s voice was not raised, not angry or menacing, rather genial, in fact, but the thing pressed against Philip’s ribs was not genial. Nor was it an instrument encouraging one to dispute.

“Git up,” the stout man repeated, and Potter obeyed sullenly.

Philip struggled to his feet, scowling. “I told you to keep out of this,” he said to Potter. “You’re one of them that won’t take advice. You come beggin’ for it, and now you’re gettin’ it.... You boys keep him here an hour—after that I don’t care what becomes of him.... Then you better beat it. The government dicks are wise to us. I guess the circus is over.”

“One hour?” said the stout man.

“That’ll be plenty.”

“He will stay—like goot young man,” said the stout individual, pleasantly. “You go along, mit nottings to worry.”

Philip went first into the rear portion of the house, where the living quarters of the proprietor had their location—judging, at least, from the odor of cookery. He remained five minutes, then reappeared. He had done the telephoning he had come to do.

“Don’t let him make his getaway,” he said, as he went out of the door.

“I t’ink you should better go in der back room,” said the stout man, and Potter obeyed reluctantly.

“How about getting away yourself?” he said. “Doesn’t that interest you?”

“You should worry. In one hour you can go. Den I look out for meinself.”

Potter sat down in a rickety chair, a very disgusted young man. He was a blunderer. From the first he had blundered. And now his blundering promised to bring all his discoveries to nothing. Cantor would escape, others, duly warned, would escape—all, doubtless, to carry on their work elsewhere in the country. So much for rushing into things headlong.... He wondered what Downs was doing. There was but one ray of light in the affair—Cantor’s work was interrupted, his organization broken up. But that was little when compared to what might have been accomplished if he had worked with his intelligence instead of his impulses. It is no pleasant experience for a young man of Potter’s make-up to find himself ridiculous, and he felt he was ridiculous—held a futile prisoner by a stout old German who seemed to regard the whole thing in a humorous light. He scowled and applied a well-selected list of names to himself.

He never knew before how long sixty minutes could be. From time to time his guard peered owlishly at a fat silver watch and announced the passage of time.

“Vell, we wait fifteen minutes already,” he would say, or, “Perty soon we keep company halluf an hour.”

At last the hour came to an end; the stout man replaced his watch in his pocket. “You should go now if you like,” he said. “I got no more use for you here, eh? You run along now, und maybe you keep out of troubles.” Evidently the man did not take him over-seriously, and it enraged Potter. The stout man chuckled. “Und don’t worry apout me, please. Goot-by.”

Potter was accompanied to the door, and the stout man stood by, his right hand concealing something in his pocket, until Potter started his car and drove away. Then he vanished with suddenness.

Potter was at a loss. How should he proceed now? Should he go in search of Downs to report his fiasco, or should he go ahead on some plan of his own? The lesson he had just received was forgotten. He had no stomach to see the look that would come over Downs’s face when he made his report. No, he would do something. He would not come back empty-handed. He would not go back until he had something to show for his afternoon’s work. He had set out to catch Philip, and he would stick to it until he did keep Philip. Such are the ways of head longitude, if one may name it so.

The one place Potter could think of where trace might be had of the man was where he lived—over Herman von Essen’s garage—and he took that as his destination. Ten minutes brought his car to the von Essen driveway and he turned in. His headlights cut through the dusk to the doors of the garage, for the short winter afternoon was speeding toward darkness. As he leaped out of the car he noted that the house was dark and paused a moment to peer from one window to another. No light was visible, and he wondered at it. His objective, however, was the garage, and he hastened toward it. The doors were locked. Through the window he had used the night before he looked in and could make out the presence of both the von Essen cars.

He went to the door that gave on the stairway leading up to Philip’s quarters, rapped, waited, but received no answer. He tried the door. It opened to his turn of the knob, and he climbed the stairs with what stealth he was capable of. He found no door locked. No one was in the rooms, which were in a state of confusion. Their condition was that of rooms hastily ransacked by a tenant snatching what was valuable and most convenient in unexpected flight.

He descended and went to the rear door of the house. No one answered his ring or his knock. He was beginning to be affected by a sense of strangeness, by a certain numbing portent which seemed to weight the very air. The hairs at the back of his neck felt as though they were striving to stand erect, as if a chill breeze were touching them. He retreated from the door and peered at the house, at its lightless windows, its massive blackness against the evening sky. It wore a deserted, forbidding, secretive look; the look of a house concealing something awful within it.

He was alarmed now, and his alarm was for Hildegarde. What did this thing mean? What did it mean to her? Where was she?

Now he rushed to the front of the house, mounted the broad piazza and rang the bell long and repeatedly. Not satisfied with this, he battered the door with his fists. Suddenly the door opened, and Hildegarde stood there outlined against the darkness, a wisp of a thing almost to be blown away by a breeze, he thought.

She uttered a gasp, a sob of relief. “Potter.... I prayed you would come....” She drew him into the house and closed the door behind him.