Never was a returning prodigal greeted with more delight than was Sandy when, close to dusk, with a parcel under his arm, he joined Dick and Larry inside a little Summer house in the Everdail estate grove.

“Where have you been?” demanded Larry. “We hunted high and low! We thought something had happened to you when we saw Jeff fly his airplane away, came here and didn’t locate you.”

“I didn’t mean to scare you. But I’ve been awfully busy.”

“Doing what, Sandy?”

“Following farmer boys down hot, sunny furrows while they picked vegetables for market, Dick.”

“Following farmer boys? What in the world for?”

“To ask them if their fathers would buy a book on family crests and have their coat of arms thrown in free.”

“Have you lost your head, Sandy?”
229

The youngest Sky Patrol grinned, and shook his head in question.

“No, Larry. It was an excuse to get them talking. I got the book out of Mr. Everdail’s library and used it to make them think I was a subscription agent—so I could ask questions.”

“Ask—questions?”

Dick and Larry spoke together.

“About what?” demanded Larry, and Dick nodded to show he wanted an answer also.

“Well—about who is related to who, and family scandals, and who works for this one and that one—just ‘gossip’.”

Dick caught the impish youth by his shoulders and shook him.

“Stop that! Tell us where you’ve been and what you did? We’ve worried ourselves sick, nearly.”

“I have told you.”

Then he became really serious.

He had been all over that section of the farm-lands, he asserted, to see if he could pick up any information that would give him some connection between either Mr. Whiteside or Jeff, or the mysterious seaplane passenger—and Mimi or the yacht stewardess.
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“If I knew that, I thought we could start patching clues together,” he finished. “Because Jeff has a lot to do with this mystery.”

“I think you’re right,” Dick agreed. “But what started you off on that track?”

Taking an arm of each, Sandy led them, wordless, up the path.

Spying carefully to be sure that Mr. Whiteside was not in sight, and being certain that no one else was watching, Sandy led his chums into the hangar.

Across to one of its longer sides he led them.

“These are the switches that work the rolling door motor, you remember?”

“Yes, Sandy. What?——”

“Look at them before it gets too dark, Dick. Do you see anything strange? You know as much about wiring circuits as I do. We both built amateur short-wave sending and receiving sets. You, too, Larry. What isn’t right about the switches or—the wires?”

Thus guided, both studied the switches.

All Larry saw was that the wires were of a braided form.

“But—are they?” He pulled a wire out a trifle from the sheath.

Then his comrades observed what had first attracted Sandy’s attention, puzzled him and led to further search.
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One wire, somewhat lighter in its insulation than the other, was wound around the heavier one. They traced it, as Sandy had done. It seemed to wind on down, as did others he showed, from each switch-pole, into the protective sheathing of metal and insulation; but none really were wound any further. From there on down, they ran behind the other wires!

“Bend down, close to the floor,” urged Sandy. “See all the dust and lint piled up?” He scraped some aside.

“My!” exclaimed Larry. “Golly-gracious-gosh-gravy-granny! The wires come out from behind the sheath and turn along the floor, close to the wall—and there’s dust all covering them! No wonder we didn’t notice them.”

“Where do they lead to?”

“Follow the dust line, Dick,” Sandy urged.

Back along the hangar wall they crept, until they came up to the small wooden cupboard with its dusty, frayed protecting burlap across the front. Under the cupboard boards the wires ran well concealed by more dusty lint which seemed to have been swept into the corners by the lazy act of some cleaner.
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“Inside here—but don’t use a light—inside here, there are smaller duplicate switches for the electric light arc and the motors,” Sandy informed his breathless, admiring cronies.

They easily proved it. More, they located the wiring in the dusk.

“But how does Jeff get in and out of here?” asked Dick.

“We have to go outside so I can show you what I discovered.”

Trooping around to the rear, at one corner, Sandy bade them bend down and examine the bolted metal sheaths, large plates of sheet iron, that composed the walls of the edifice.

“I don’t see anything,” objected Dick, dejected that he had not been as quick of wit as had his younger chum. “But, then, you saw it first by daylight.”

“I did, that’s so.” Sandy gave them all the information he had. “I saw a break in the paint, only up one-half of this big plate of iron.

“The bottom half pushed inward,” he explained. “It has hinges fixed to the inner part so it will lift up into the hangar and we can creep in.”

He proved it, and they followed him through the fairly low orifice.
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“Now,” he said, as Dick, last to crawl in, cleared the edge of the metal, “see how clever this is—the inside of the two plates it has to come down against are fixed with something soft—I think it’s felt—to keep the plate from clanging. It fits so well that the only way I found out about it was by the sun making the dent in the paint show up a few little bright worn spots of bare metal.”

They complimented him with no trace of envy.

“Do you think Jeff did this?”

“Well, Larry, he said he flew over here at night. He chews gum and we saw how fast he chewed the day he pretended to be forced to land here. He knew all about the emeralds. And the most telling thing against him is that his wife—Mimi—is Mrs. Everdail’s maid and was on the yacht——”

“Mimi his wife?”

Sandy nodded at Dick&rs............