About eight o'clock the following morning while her friends were still sleeping, Linda Carlton, clad in a bathing-suit and a beach robe, dashed down to the lake. She thought an early morning swim before anyone was up would clear her brain and give her a chance to think over her plans and come to a decision. If possible, she meant to get in touch with Ted's company before the detectives arrived at his home to arrest him.

She had thought, naturally, that she would find the lake deserted, for everybody ought to be tired out after last night's party. She was therefore amazed and a little annoyed to see some one else already in swimming.

"I'll go in the other direction," she decided, but before she was even in the water she heard a familiar voice calling her.

"Linda!" cried Louise Haydock, waving her arms, and starting to swim rapidly towards her. "Ho—Linda!"

"Lou!"

"Yes—me!" shouted the other girl. "But did you say 'Who' or 'You'?"

"I said 'Lou'!" replied Linda, laughing good-naturedly. It was a relief to find the other bather was her chum.

They were within talking distance now, and Louise hurried to the shore. They sat down together and gossiped about the party, Louise laughing over Ralph's childishness in trying to keep up the quarrel with Linda.

"To tell you the truth, Linda," she added, "I'm bored with him. As a matter of fact, I'm fed up with most of the boys. Harry's all right, but he has so little time. All the others are so pleased with themselves. They think we can't get along without them!"

"Well, can we?" teased Linda.

"Why not? Except for dances——"

Linda dug her toes into the sand and smiled.

"That's the trouble with us. There's always some 'except.' We ought to make up our minds to stay away from dancing, if we really want them to get over their superiority complex."

"It would be pretty dull in the evenings—we'd have to find something else to take its place...." Louise paused to watch an airplane that was flying overhead. "Linda!" she cried, abruptly, "I have it! Let's go off on a trip—just the two of us—in your plane! Be gone a week or two!"

Linda grabbed her chum's hands in delight. What a marvelous idea! The freedom! The adventure of it! And she could link it up with her own errand to Kansas City.

"Oh, I'd adore that, Lou!" she exclaimed. "Would you really trust yourself to me? Honestly? You wouldn't be afraid?"

Louise put her arm about the other girl and hugged her tightly.

"Of course I would! I have an awful lot of confidence in you. And I'd love it!"

Linda's brow darkened suddenly. For as always, she had to think of others besides herself.

"What's the matter?" demanded Louise, watching her companion's face.

"I am thinking of Aunt Emily—and your mother," answered Linda. "Wondering whether they'd give their consent—and if they did, would they worry themselves to death?"

"Mother would be all right—I can manage her, and Dad too," said Louise confidently. "And, after all, think of the flying that girls do now-a-days. A little picnic like this is tame, compared to flying from England to Australia."

"Yes, I know—but Aunt Emily's so scary about planes."

"Well, I tell you what we could do—we could map out our whole trip beforehand, and decide where we would land each night. We could probably get the names of the hotels where we would stay. And each evening after supper, we could telephone the people at home."

"That's an idea!" agreed Linda, enthusiastically.

"You wouldn't want to camp out, anyway, would you? They would be sure to object to that—just two girls alone."

"No; we'd have to buy a lot of equipment, and I'd hate to load down the plane. But I'm afraid Aunt Emily would even object to our staying alone at hotels. You know how particular she is."

Louise was silent a moment, thinking it was too pleasant an idea to give up at once. She'd have to devise a way out of their difficulty.

"I'll tell you," she announced, finally. "We can plan to stop with people we know each night—or at a hotel where some friend is staying. We surely can round up some relatives and friends!"

"That's it!" cried Linda, joyfully. "That ought to be easy! And we can send telegrams ahead. But the places will have to have some sort of airports."

"Oh, most every town has some kind of landing place," said Louise. "I don't think that need worry us."

"There's another thing," added Linda, slowly. "I'd want to start today. Because I must go to Kansas City as fast as I can." And she explained to Louise her plan about establishing Ted's alibi.

Louise leaped into the air in her excitement and approval.

"That's great! You know me, Linda—I always hate to wait about anything. We can pack our suit-cases and send our wires in an hour if we hustle. Hurry up! Hop in for a dip, and come right back!"

Ten minutes later they dashed breathless and wet into the dining-room of the Carlton bungalow, where Miss Carlton was eating a leisurely breakfast. In their excitement over their idea they could scarcely explain it. But at last the older woman understood; she heard them out, and gave her rather reluctant consent.

"If you don't make the trip too long," she added.

"A week?"

"Isn't four days enough? Then we would have to arrange only two stopping places—the same one coming back. And I am sure I could do that very easily."

The girls agreed, delighted even with a compromise. Nothing they had ever done promised to be half so thrilling.

They would fly southwest, making their first stop Kansas City, where Ted's firm was located. Searching through her address-book, Miss Carlton remembered that she had a cousin living in a hotel in that city and she wired her immediately to reserve a room for the girls for that night, and to chaperon their visit.

"And then we'll fly to Sunny Hills—as our destination!" cried Louise, with happy inspiration. "It's in Colorado—where my Aunt Margaret and Uncle John live! Oh, we'll have no end of fun there!"

"You're sure they won't mind?" asked Linda.

"They'll be tickled to death. They have a huge place—sort of a farm—and six children. Of course they're not children now—several of them are married—but they always keep open house. We used to go there a lot when I was a kid."

"All right—you send that wire," agreed Linda, as she hastily swallowed some food, "and I'll get ready and go down to my plane, and see that it's O.K."

"How about some lunch?" suggested her Aunt Emily.

"Oh, yes, please—if you don't mind!"

In an incredibly short time the girls were dressed, their suit-cases packed, the wires sent, and the lunch in readiness. About half-past ten, without saying a word of good-by to anyone except Miss Carlton and Louise's parents, they took off.

The sky was clear and blue, without even a cloud to threaten them with fog or storm. It was Louise's first ride in a plane, yet she was not a bit afraid. She said she had never been so thrilled before.

"I'm getting the craze, Linda!" she shouted, above the noise of the motor. "If I only had a suit like yours!"

She was wearing her riding-breeches and a tan sweater-blouse, with a close-fitting hat of the same color—a costume, which though neat and appropriate, had none of the style and charm of her companion's.

"But you can't wear earrings!" teased Linda, pulling at Louise's ears to make sure that the other girl heard and understood what she was saying.

"In the suit-case!" returned Louise, laughing and pointing towards the article she named.

But neither of the girls wanted to try to talk. They were content to rise higher and higher into the air, to feel the glorious sensation of smooth flying, knowing that everything was just right. Both of them began to sing.

On, on they went, over fields and towns, watching their map and their instruments, dipping now and then to catch a glimpse of the landscape below, climbing back to the heights for safety. As the clock on their plane neared twelve, they realized they were hungry, because breakfast had been such a sketchy affair for them both. Louise untied the box, and they ate joyously. Their first meal in the air!

It was still early when they arrived at Kansas City, and Linda flew a straight, swift course to the large grounds that were occupied by the company for which Ted Mackay worked. Without the slightest mishap or difficulty Linda brought her plane to a perfect landing in the large area set aside for that purpose.

A nice-looking young man in a flyer's uniform came to them in welcome. His face showed no surprise; it was evidently an every-day occurrence to meet feminine pilots.

"I would like to speak to the sales-manager," said Linda, after she had answered his greeting, and made sure that this was the right place. "I want to make some inquiries about Ted Mackay."

"All right," agreed the young man. "I'll take you to Mr. Jordan immediately."

But when they were introduced, Linda felt suddenly shy. What right had she, she asked herself, to pry into Ted's affairs? She wasn't a relative—or even a friend, if she adhered to her father's command. So it was Louise who came to the rescue, as she always did in emergencies, and proceeded to take charge of the interview.

"You see," she explained, "the people who had that valuable necklace stolen are pretty much perturbed over the whole affair—and naturally they hired detectives. Well, Mr. Jordan—you know what detectives are! They bungle everything."

"Yes?" remarked the man, looking smilingly from one girl to the other, thinking that they, too, were rather excited.

"And just because they found Mr. Mackay by the stolen plane, and because they located a gasoline agent who swears that he sold gas to a red-haired man for that same plane earlier in the day, they're sure Mr. Mackay is a thief."

"And they're going to his home—to arrest him!" put in Linda, now more at ease.

"But they can't prove anything," Mr. Jordan assured them, calmly.

"Oh, but they say they'll put third degree on him, or whatever it is, and force him to a confession. And—and—think of his poor mother!"

"But what do you girls want me to do?" he asked. "I don't see how I can stop them!"

"We just want you to establish his alibi," explained Louise. "Write down everything Mr. Mackay did from early morning till the time he started off in that new plane."

"O.K.!" exclaimed Mr. Jordan, a light breaking over his face. "That's easy! We had a salesmen's meeting at the Winton Hotel, and lunched together. I can swear Mackay was there—and so can half a dozen others. We came back here about three o'clock, and Mackay was looking over the plane and studying his maps for about half an hour. Then he took off—for Buffalo."

"That's just what we want!" cried Linda, and Louise added, "wonderful!" and squeezed the elderly man's hand. He smiled at her as if she were his daughter.

"And will you dictate that to a stenographer, and send a copy to Ted by air-mail?" urged Linda.

"Certainly," he agreed.

"And now," added Linda, "will one of your mechanics look over my plane and put it away till tomorrow? We want to get our suit-cases, and taxi to my cousin's hotel."

So, half an hour later, when the girls were making themselves known to the elderly couple who were expecting them, they spoke joyously of the perfect success of their first day's adventure, but they did not mention their mission on Ted Mackay's behalf.