It was finally decided that Dorothy and Bill should make a series of circular patrols, centering above New Canaan.

“We’ll each take a plane,” said Bill, “and keep each other in sight.”

“What’s the use of doing that?” Dorothy asked. “Why not make the patrols separately? When I come down, you go up. In that way we can stay in the air twice as long on the same amount of gas, and take a rest once in a while.”

“Too risky. These smugglers are desperate. We’ve already thrown a good-sized monkey-wrench into the works of their organization. That Mystery Plane is quite likely to pack along a machine gun—and use it if the pilot finds out we’re trying to follow him.”

“Are we going up unarmed?”

“You are—but I’m not.”

Dorothy raised her eyebrows in surprise.

“Well, that’s nice of you!”

“Look here, young lady,” cut in her father. “I don’t know what Bill’s plans are, but if you’re going on these patrols, just remember that he is the captain of the outfit and must have obedience. Otherwise, I’ll not consent to your going at all.”

“Oh, I’ll be good, Daddy. But I do think—”

“But you mustn’t! Your job is to do what you’re told and let your captain do the thinking.”

“You see, Dorothy,” explained Bill, “in order to use a gun in the air, a pilot must have training and practice. Otherwise, all you do is to draw the enemy’s fire. If we meet up with this bird you’ll have plenty to keep you busy—a very important part to play. But if there’s any gunning to be done, I’ll do it. Before we go up, I’ll outline exactly what we’re to do in the event we sight the gang’s airplane.”

Dorothy got out of her chair.

“How about getting busy, then?” she suggested. “The longer we’re up, the more we are likely to accomplish.”

“Hold your horses,” laughed Bill. “Don’t think for a minute we’re going to patrol all day long.”

“Why not?”

“Waste of time.”

Dorothy plumped herself down in her chair again.

“Oh, all right. Have it your way. Personally, I can’t see doing a thing at all, unless one does it properly. You and your plans make me tired.”

“Don’t get peeved,” he bantered. “These won’t be endurance flights.”

“They won’t be anything at all unless we find that plane and you can’t expect it to take the air just when you want it to!”

“Stop quarreling, children,” admonished her father. “Bill knows what he is talking about.”

“Well, maybe he does. He can catch the old plane by himself. I’m through.”

“What you need is another nap, young lady. You’re tired and cross.”

“I’m not. Men always club together.”

“And what can a poor girl do?” supplemented Bill with a grin.

“Stop teasing, Bill!” commanded Mr. Bolton. “Apologize to Dorothy and tell her why you mean to take short hops. I can’t see the sense in such procedure myself—any more than she can. And just remember that an overdose of excitement puts anybody’s nerves on edge. She’s been through a lot more than you have during the last few days.”

At his father’s words, Bill’s face wore such a look of honest contrition, that Dorothy’s conscience smote her. They both began to speak at once.

“Gee, I’m sorry, Dorothy—”

“I’m an idiot, Bill—”

They burst into laughter simultaneously.

“Now we can get on with our discussion,” smiled Dorothy. “Go ahead, Bill.”

“Well, the smuggler’s pilot has been taking most of his flights—or I ought to say, the flights we know about—during the late afternoon. I haven’t the slightest glimmer why he chooses to fly at that time. But, as I see it, if he has done it day after day in the past, the chances are he’ll continue to leave his hangar at about the same time. My plan is for us to take off at about four each afternoon. We can remain in the air until six. If he comes from around here, we’d catch him shortly after he takes the air. That’s how I figure it.”

“Maybe you’re right.” Dorothy was still unconvinced. “But how about the warning we got a little while ago?”

“What’s that got to do with it?”

“Well, we hadn’t had lunch yet—he dropped the message from his plane in the morning—not during the late afternoon!”

Bill yawned unblushingly and got to his feet.

“Cuts no ice,” he asserted. “That wasn’t a regular hop.”

“What then?” This from Mr. Dixon.

“A grandstand play, pure and simple. Those lads haven’t the brains I gave them credit for, if they really think they can steer us off with tripe like that!”

Mr. Bolton ground the butt of his cigar on an ashtray, and rose.

“Perhaps that wasn’t the idea,” he suggested.

Three heads were turned sharply toward him.

“What do you mean, Bolton?” asked Mr. Dixon.

“A come-on,” returned his neighbor.

“A come-on?” echoed Dorothy in a puzzled voice.

“Just that—nothing more nor less.”

“I get you,” Bill nodded. “Get us in the air, by that teaser—rely on us to go after the Mystery Plane as a matter of pride—and then fill us full of machine gun bullets. If they start anything like that—well—two can play the game and if that lad with the beard can’t shoot any better than he handled his plane when he zoomed the house just now—it is, as the French say, ‘to laugh’!”

“That’s all very well,” argued Mr. Dixon. “I don’t mind Dorothy flying, but I do draw the line at machine guns. That’s no game for girls. You keep your two feet on solid earth until this business is over, my dear.”

“Oh, Daddy!” Dorothy’s voice was full of disgust.

“Sorry, daughter, but I simply can’t let you take the risk.”

Mr. Bolton placed his hand on his friend’s arm.

“You know, I don’t think that Bill would have countenanced Dorothy’s going on patrols with him unless he felt assured she would run no danger. How about it, son?”

“If she does get into trouble, it won’t be with my consent,” he smiled. “But seriously, sir,” he turned to Mr. Dixon. “There will be a minimum of danger if Dorothy does as I tell her. In the first place, machine gun fire in the air is not nearly so potent as it is on terra firma. Try and hit a small object flashing by when you’re traveling like a bat out of—ahem!—Harlem. Try it and see how many planes you don’t hit! And in the second place, that bearded guy won’t get a chance to turn his gun in her direction.”

“Well, I’m no flyer and I haven’t the slightest idea of the technicalities that must arise in aerial combat work,” Mr. Dixon made this statement slowly and thoughtfully, “but still—”

“Daddy, don’t be ridic.” Dorothy’s tone was tolerantly amused.

“Do you really think I’m foolish, my dear child?”

“Oh, pigheaded is a better word, at times, if you insist on the truth!”

All four burst into roars of mirth.

“That’s one from the shoulder, Mr. Dixon,” choked Bill. “You’d better go the whole hog, now she’s a licensed pilot!”

Dorothy’s father shook his head in pretended sorrow. “You’re all against me, that’s obvious. And there’s much too much pig in this conversation to suit a conservative parent.” He threw an affectionate glance at Dorothy. “Ever since this tomboy daughter of mine was able to grip my finger when I leaned over her crib, she has pulled her old Dad hither and yon to suit her fancy. So I suppose I’ll have to give in again—acknowledge I’m wrong, and so forth. Run along, children, and see to it your airships are in apple-pie order.”

“You’re a darling!” His daughter bestowed a hearty kiss upon his left ear.

“Beat it—you scamp!” Mr. Dixon’s voice was gruff, though his eyes sparkled with merriment. “If you bother me much longer, it will be lunch time before I get down to the bank—and I’m likely to change my mind. Shoo!”

“Ogre—I defy you!” With a laugh, she beckoned to Bill and ran down the steps.

“Well, what shall it be?” she inquired when he joined her. “Your ship or mine, first?”

“Mine, I think. None of the three has been off the apron of the hangar since I left for Europe. Frank has been looking after them. He’s a great old feller, you know. When we brought him back from New York he didn’t know a fork from a gadget. Now he’s chauffeur, general factotem around the house, and practical mechanic for me. He knows his job all right, but my boats will need more overhauling than yours.”

“Which plane shall you use for this work?”

“The Ryan M-l, that the bank gave me after that Martinelli business. She certainly is a smart little bus—can fly rings around anything in this neck of the woods. Hello—” he broke off as they came down the drive, “somebody’s had a breakdown.”

Drawn up at the side of the ridge road stood a green coupe of the type motor car manufacturers advertise as “de luxe model.” As they came in sight, a young man crawled out from beneath the body.

“Why, that’s Mr. Tracey,” said Dorothy. “Do you know him?”

“Yes, I met him at Mr. Holloway’s house one night. Isn’t he the old boy’s secretary?”

“Yes, he is. He’s quite nice. Dad sees a lot of Mr. Holloway, you know.”

The secretary, tall and sleekly blond, was looking ruefully down at his grey flannel trousers, now streaked with the dirt of the roadway.

“Good morning, Miss Dorothy,” he greeted, clipping his words in a precise manner. “Afraid I’m not exactly presentable.” Then for the first time, he appeared to notice Bill. “Hello, Bolton,” he said affably. “You’re quite a stranger around here.”

“Got back a couple of days ago,” returned Bill casually. “Need any help?”

“Thanks, no. Loose nut, that’s all.” He patted his monkey wrench with a grimy hand. “This fixed her. Doing much flying, Miss Dorothy?”

“Yes, I go up quite often. Bill taught me, you know.”

“Yes, I remember. I’d like to take lessons, myself. How about giving me instruction—that is, if you’re not too expensive?”

“I’m really not in the business,” parried Bill. “You’d do much better at one of the schools. Glad to give you a hop, though, if you’d like to go up?”

“Thanks so much. I’ll be glad to take advantage of your offer. What about this afternoon? It’s a perfectly lovely day.”

“Sorry, but today I’m overhauling my planes. Been away some time, you see. I’ll probably take them up on tests about four. But of course I don’t want the responsibility of a passenger until I know they are running O.K.”

Mr. Tracey nodded and got into his car.

“I understand perfectly. Thanks for the invitation, though. I’ll give you a ring later in the week and allow myself the pleasure of going up with you. Goodbye. Goodbye, Miss Dorothy.”

With a wave of his hand the car moved off and Dorothy turned to Bill.

“Why did you tell him you were going to take the air about four?” she asked.

“Because if the smuggling gang know what I’m going to do it will save time if we pull off our little scrap this afternoon.”

Before this admission Dorothy had looked puzzled. Now her eyebrows went up in startled astonishment.

“Good Heavens, Bill! You surely don’t think that Mr. Tracey has anything to do with that! He’s as prim and prissy as a pussy-cat!”

“Just my opinion. Of course he knows nothing about the diamonds. But your prissy boy friend has the reputation of being the worst gossip in New Canaan. When he takes those gray bags of his to be cleaned, it will be all over the village that Bill Bolton is back and intends to test out his planes late this afternoon.—And that is just what I want.”

“Oh, I see,” Dorothy nodded thoughtfully. “But I’ll tell you one thing. If we are going up today, it’s high time we quit talking and got busy on the planes.”

With four airplanes to groom, the next few hours proved busy ones for both Dorothy and Bill. But by four o’clock everything was ready for their flight.

“Got your instructions down pat?” he inquired as Dorothy got aboard the Will-o’-the-Wisp. The airplane was resting on the concrete apron of the Dixons’ hangar, preparatory to the take off.

“Know them backwards,” she flashed with a smile.

“Good luck, then.”

“Good luck to you, Bill.”

He stepped swiftly to one side as she switched on the ignition. For a moment or two he stood there watching her amphibian taxi away from the hangar, gathering speed as it went. Then when the wheels left the ground and the big bird of wood and metal soared upward, he turned away and made off in the direction of his father’s property.

As Will-o’-the-Wisp climbed in great widening circles, Dorothy at the controls knew she had plenty of time to gain the position agreed upon before Bill could get under way. The air was smooth and still, without the slightest breath of disturbing wind. Perfect flying weather and wonderful visibility with a clear blue horizon unmarred by the smallest shred of cloud.

The Boltons had turned the ten-acre pasture behind their house into a level flying field. The old hay barn had been enlarged, partitions removed and a concrete floor laid. It now made a large roomy hangar, for their three planes.

Looking down as she kept on circling higher and higher, Dorothy saw Bill cross the ridge road and appear a moment or two later on his own flying field. She watched him hurry down to the hangar and could see Frank busy about the Ryan before its open doors. Then she saw Bill get aboard. When she looked again, his small monoplane was already in the air.

By this time the indicator on Will-o’-the-Wisp’s altimeter marked a height of between eight and nine thousand feet. According to instructions, Dorothy leveled off and bringing right rudder and right aileron simultaneously into play, she sent the plane into a wide circular turn. Far below, the Ryan was pursuing the same tactics, so that both planes were cruising over the township of New Canaan.

Dorothy and Bill continued to maintain the same relative positions for the next fifteen or twenty minutes. Then as Will-o’-the-Wisp swung round toward the west, Dorothy spied a third plane, streaking toward New Canaan at an altitude of some three thousand feet.

The fact that Bill had also spotted the intruder was evident, for he began to climb.

“Bill’s advertising plan worked,” muttered Dorothy with satisfaction. “If that amphibian over there isn’t the Mystery Plane, I’ll eat my ailerons!”