Lawrence could scarcely credit his good fortune. After a little he tried to change his position, and found that he was so cramped that he could scarcely move. Carefully he took his pocket flash out of his pocket and, turning it around, acquainted himself with the position of the doors. He also saw the cigarette which the Rattlesnake, as Lawrence henceforth called “Mr. Smith,” had dropped, and he crawled over and put it in his pocket. Then with the utmost caution he made his way back to the small door which still swung open, and with a smile at the carelessness of the men, he made his way out. He had gone a hundred yards perhaps when a thought struck him, and he retraced his steps. Once more entering the hangar, he approached the machine nearest him, paused beside it for five or ten minutes, passed on to the next where he stood for the same time, and then went to the big dirigible. With a chuckle he waved a hand at the silent aircraft, and for the last time passed through the door. This time he closed it, and finding a spring lock hooked carelessly through a strong staple, he adjusted it and clasped the lock. The hangar was securely fastened. Lawrence judged, and correctly, that when the men returned in the morning each would think that one of the others had closed and locked the small door, and not caring to be caught in so flagrant a piece of carelessness, not one would confess that he had forgotten it.

As for the boy, he sped rapidly back across the country he had traversed earlier in the evening and by great good fortune caught a train to Washington about two minutes after reaching the little station. As no one had seen him arrive, his departure was not noteworthy.

Lawrence was tired out when the train reached Washington, and he thought with dread of the long trolley ride to the Heights, when he happened to remember that he was now able to afford any number of taxis. He stepped into one at the door of the station, and luxuriously giving his street and number, he leaned back and dozed all the way home.

O’Brien was there before him, a worried man.

“Now then,” said he, “where have ye been the while?” He shoved a chair toward Lawrence and offered him a ham sandwich from a paper bag. Lawrence took it eagerly. “You look dead beat and starved and ginnerally tired out. What’s the word?”

“You are going to be mad,” said Lawrence, “because you told me not to do something and I did it.”

“Then consider me frothin’, and tell me what’s what and get it over with. Sure, these fits of temper are bad for me heart.”

“All right,” said Lawrence, and he proceeded to tell O’Brien his evening’s adventure. When he produced the cigarette O’Brien took it with careful fingers.

“Whew!” he said as he examined the paper, smelled the tobacco, and tried to make out the interwoven letters of the intricate monogram.

“It looks like r’yalty,” he said finally. “Those same cost, me boy, they cost! I only wish you had had a look at the gentleman. Well, I should say you had a narrow escape. I don’t like it all the same, although we know more than we did. Mr. Ridgeway is a bit close, too. We didn’t know it was jools like that that we were handlin’, did we?”

“We haven’t handled them yet,” said Lawrence. “But I reckon they are just where Mr. Smith said they are, and it looks as though we were going to have to cart them somewhere or other. I don’t see why we take the dirigible,” said Lawrence, “when the planes are faster.”

“There is some good reason,” said O’Brien. “For instance, that dirigible will carry a crew large enough to give a pretty good fight if it was necessary. That’s one thing. Another is that Mr. Ridgeway doesn’t know that they know anything about the freight he is to carry. Gee, there is a leak somewhere! That’s one thing. Now to bed with you, me wild adventurer, and get some sleep what’s left of the night. We will have to see Mr. Ridgeway the morn, so he can talk to us. I called there tonight and found him much better. Get you to bed, and don’t talk. I want to think. Somewhere or other I have seen a mate to this cigarette.”

He carefully wrapped it in a bit of paper and put it in his cigar case. “That’s a good souvenir,” he remarked, nodding his head.

Lawrence tumbled into bed. He was too tired to realize the narrow escape he had had, and wanted nothing more than a good sleep. He did not realize his fatigue either, and when he awoke in the morning he found that what he had thought was the dimness of early dawn was the darkness of closely drawn blinds. O’Brien had tricked him. There was a note on the dresser, and Lawrence read:

“Dear Lawrence:

“There’s no place so safe for a lad of your tendencies as the same cot you are snoring on at this second. I leave you to your dreams and hope they are sweet. As for me, I am pulling down the blinds and disconnecting the telephone, and then I am makin’ off: for I have a pretty idea all of my own. I will see you later. By the way, you took my gloves last night, and I can find but one. If you have lost that glove it costs you a pretty penny, gloves being in a high altitude since the late war. Good-bye. Go see what is happening to the dirigible, go see Mr. Ridgeway, go to a movie, go have a good time however you like but don’t you dare follow any clues today. Against orders, and meet me here; HERE, mind you, at seven tonight. I may have news.

After he had had a meal which was neither breakfast nor luncheon, but combined all the most agreeable features of both, commencing with grapefruit and cereal and ending with pie, Lawrence went out to the Aviation Field, where he found the men busily working on the dirigible. A week at most would find it in working order again. O’Brien was not there. After taking a little flight in his favorite plane, a flight which took him over the scene of last night’s adventure, he came down, and returned to the apartment where he loafed and read until seven, when O’Brien came in.

“I flew over that field again this afternoon,” said Lawrence. “I did not see a soul.”

“That’s all right,” said his friend. “I have been there all day meself in a tree-top, with a pair of glasses strong enough to spot the Queen of England powdering her nose from the base of the Statue of Liberty. There was not a sign of ’em and I have it all worked out. They know we can’t use the dirigible, and of course by now they know the minute when it will be in shape again. So why work? Why hang around that bleak spot? And Mr. Ridgeway being laid up, there’s no use for Mr. Smith to sit with his ear glued to the listening post down there below Ridgeway’s office. No. It’s all hands take a vacation, and I’m thinkin’ I will do the same. I am going on a still hunt for our dear little book agent.”

“I forgot to tell you,” said Lawrence, “that before I left there last night, I fixed all three machines so they won’t fly very soon. I learned a few twists back in the aircraft factory, and I can put a plane out of tune so no one will guess that it has been touched, but there is the mischief to pay. And I touched up the dirigible too. Just a screw or two loose, and a couple of pinholes where they will do the most good.”

“You are like a woman’s postscript,” said O’Brien. “All the meat of the letter in it.”

“I meant to tell you before,” said Lawrence. “Well, if you are going after the Smith man, what am I to do?”

“Go see Mr. Ridgeway and tell him all this you have told me. Take the cigarette; it’s evidence.”

“Suppose we go to the theatre tonight,” suggested Lawrence. “I have not seen a show in a month of Sundays.”

“Sunday is no day to go to shows on, anyhow,” said O’Brien with mock severity. “But this bein’ a weekday it’s not against me conscience to accompany you.”

They decided on the vaudeville, and securing good seats settled down to an evening’s enjoyment.

At the beginning of the second act two men came in and took the seats just behind them. As they fumbled for the hat-clips under the seats and leaned close to O’Brien’s broad shoulders, Lawrence heard one say to the other, “Did you bring the key to the hangar?” and the other answered swiftly, “No; Mr. Smith took it.”

Lawrence felt his blood stop in its course. For a moment he could scarcely breathe. Two of the mysterious men were behind them! He dared not say much to O’Brien, but he whispered, as the orchestra blared out a jazz accompaniment to a dancer: “See who is behind you?”

O’Brien turned. To Lawrence’s utter amazement, he nodded gaily and said, “Good evenin’, Brown! A good show, I’m thinkin’.”

“It seems to be, Mr. O’Brien,” said the slow, deep voice Lawrence so well remembered.

The boy’s head whirled. O’Brien knew the man!

Between the acts, in the intermission, Lawrence led the way out to the sidewalk. He was shaking.

“Those men!” he managed to stutter. “Those men behind us! They were in that card game!”

“Crazy!” said O’Brien calmly. “The big one works at the Aviation Field. He’s a good worker, but mortal stupid.”

“Oh, believe me, O’Brien!” begged Lawrence. “I know them both. They were sitting so I could see their shapes, and just now I heard the big one ask the other if he had the key to the hangar, and he said, no, Smith had it.”

“Why, I know the man,” insisted O’Brien again. “He don’t know enough to be in a plot.”

“That’s just what Smith said,” said Lawrence. “He said they could be feet and hands, and he would be the head. That is why everything goes wrong with the dirigible. He is right there where he can do what he likes, and you trust him.”

O’Brien laughed and patted the boy on the shoulder. “This thing is getting on your nerves,” he said soothingly. “However, come back and have another look at your two friends.”

“No,” said Lawrence. “You go back, and I will wait outside, and when they come out I shall follow them. They don’t know that we came together. We didn’t talk much and they will just think I met you in the theatre.”

“Have it your own way,” said O’Brien. “I will say the remarks were suspicious enough, but I tell you, man, I know that fellow.”

“All right,” said Lawrence doggedly. “I mean to know him, too, before I get through with him. I have not seen him at the Field since I came. Where does he keep himself?”

“Dunno,” said O’Brien. “I will find out.”

He went back into the theatre and sat down. As soon as the curtain went down on the next act, he turned and spoke to the big man.

“Are you working at the Field yet, Brown?”

“No, I quit a week ago,” said Brown, leaning forward. “I couldn’t stand the foreman they have out there. A mean, suspicious lunkhead, always snooping around and giving orders.” He laughed uneasily. “So I quit.”

“Out of a job, are you?” said O’Brien.

“Yes, I am,” said Brown.

“Well, I don’t blame you much,” said O’Brien. “That foreman is a disagreeable cuss. If I can help you any way, let me know.”

“Thanks,” from Brown. “I am thinking some of going away. If I stay here I will let you know.”

“Do!” urged O’Brien. “I wouldn’t like to miss seein’ you.”

The next act came on, and O’Brien turned to the stage. He missed seeing the glance that passed from one man to the other, and chuckled as he thought of the fancy Lawrence had had. When the show was over, the two men walked down toward the cafÉs, and O’Brien was amused to see the slight figure of Lawrence sliding along after them. His collar was turned up, and his soft hat had disappeared. In its place was a plaid cap.

“Detective stuff!” laughed O’Brien. “The kid is having the time of his life. But it does seem queer. However, there’s no distress about the affair so long as I can see. We wait our chance, and off we go with our precious bundles when they are not looking. It is too simple to be funny. They have overstepped with their slugging Mr. Ridgeway and cutting up our dirigible. They can’t hurt us now. Forewarned is forearmed.”

He strolled along until he came to The Willard, where he went in and approaching the news stand commenced to look for a magazine that was adventurous enough to suit his fancy. As he stooped, the man beside him let a cigarette fall from his hand. Someone had jostled him. It dropped directly under O’Brien’s eyes, and gleaming up at him he saw the intricate gold monogram of Smith’s cigarette. Before he could straighten up and face the man, a foot was planted on the cigarette and he rose to see no one but an old gentleman beside him smoking a fat black havana. It was certainly not Smith. Besides, a voice loudly proclaimed the old gentleman as “Hemmingway, old boy,” and O’Brien, furious with his luck, hung around the lobby for hours, hoping for another chance to see the expensive monogram and delicate cork tip.

After awhile he gave up and went back to the apartment that he now shared with Lawrence.

The boy was there before him, walking the floor in a great state of excitement.

“Well, O’Brien,” he burst out, “I ran them down!”