One bright sunny morning, very early, four children stood on the rough grass of a big airfield, watching two men busily checking the engines of a gleaming white aeroplane.

The children looked rather forlorn, for they had come to say good-bye to their father and mother, who were to fly themselves to Africa.

“It’s fun having a famous father and mother who do all kinds of marvellous flying feats,” said Mike. “But it’s not such fun when they go away to far-off countries!”

“Well, they’ll soon be back,” said Nora, Mike’s twin sister. “It will only be a week till we see them again.”

“I somehow feel it will be longer than that,” said Mike gloomily.

“Oh, don’t say things like that!” said Peggy. “Make him stop, Jack!”

Jack laughed and slapped Mike on the shoulder. “Cheer up!” he said. “A week from today you’ll be here again to welcome them back, and there will be cameramen and newspaper men crowding round to take your picture — son of the most famous air-pilots in the world!”

The children’s father and mother came up, dressed in flying suits. They kissed and hugged the children.

“Now, don’t worry about us,” said their mother. “We shall soon be back. You will be able to follow our flight by reading what the newspapers say every day. We will have a fine party when we come home, and you shall all stay up till eleven o’clock!”

“Gracious!” said Jack. “We shall have to start going to bed early every night to get ready for such a late party!”

It was rather a feeble joke, but everyone was glad to laugh at it. One more hug all round and the two flyers climbed into the cockpit of their tiny aeroplane, whose engines were now roaring in a most business-like way.

Captain Arnold was to pilot the aeroplane for the first part of the flight. He waved to the children. They waved back. The aeroplane engines took on a deeper, stronger note, and the machine began to move gently over the grass, bumping a little as it went.

Then, like a bird rising, the wheels left the ground and the tiny white plane rose into the air. It circled round twice, rose high, and then sped off south with a drone of powerful engines. The great flight had begun!

“Well, I suppose the White Swallow will break another record,” said Mike, watching the aeroplane become a tiny speck in the blue sky. “Come on, you others. Let’s go and have some lemonade and buns.”

Off they went and were soon sitting round a little table in the airfield’s restaurant. They were so hungry that they ordered twelve buns.

“It’s a bit of luck getting off from school for a couple of days like this,” said Mike. “It’s a pity we’ve got to go back today. It would have been fun to go to a cinema or something.”

“Our train goes from London in two hours’ time,” said Peggy. “When does yours go?”

“In three hours,” said Jack, munching his bun. “We shall have to go soon. It will take us over an hour to get to London from here, and you girls don’t want to miss your train.”

“We’ll all look in the newspapers each day and see where Mummy and Daddy have got to,” said Peggy. “And we’ll look forward to meeting you boys here again in about a week’s time, to welcome the plane back! Golly, that will be exciting!”

“I still feel rather gloomy,” said Mike. “I really have got a nasty feeling that we shan’t see Dad and Mummy again for a long time.”

“You and your nasty feelings!” said Nora laughing. “By the way, how’s Prince Paul?”

Prince Paul was a boy at Mike’s school. He and the children had had some strange adventures together the year before, when the Prince had been captured and taken from his land of Baronia to be kept prisoner in an old house that had once belonged to smugglers. The children had rescued him — and now Paul had been sent to the same school as his friends, Mike and Jack.

“Oh, Paul’s all right,” said Mike. “He was furious because the headmaster wouldn’t allow him to come with Jack and me to see Dad and Mummy off.”

“Well, give him our love and tell him we’ll look forward to seeing him in the holidays,” said Peggy, who was very fond of the little Prince.

“Come on — we really must go,” said Mike. “Where’s the taxi? Oh, there it is. Get in, you girls, and we’ll be off. Jack and I will have time to come and see you safely into your train.”

Before evening came all four children were safely back at their two schools. Prince Paul was watching for his friends, and he rushed to meet Jack and Mike.

“Did you see them off?” he cried. “Did you see the evening papers? There’s a picture of Captain and Mrs. Arnold in it.”

Sure enough the evening papers were full of the big flight that the famous pilots were making. The children read them proudly. It was fun to have such a famous father and mother.

“I’d rather have a famous pilot for a father than a king,” said Prince Paul enviously. “Kings aren’t much fun, really — but airmen are always doing marvellous things!”

For the next two days the papers were full of the plane’s magnificent flight — and then a horrid thing happened. Mike ran to get the evening paper, and the first thing that met his eye was a great headline that said:

“NO NEWS OF THE ARNOLDS. STRANGE SILENCE. WHAT HAS HAPPENED TO THE WHITE SWALLOW?”

The White Swallow was the name given to the beautiful aeroplane flown by Captain and Mrs. Arnold. Mike went pale as he read his headlines. He handed the paper to Jack without a word.

Jack glanced at it in dismay. “What can have happened?” he said. “I say — the girls will be jolly upset.”

“Didn’t I tell you I felt gloomy when I saw Dad and Mummy off?” said Mike. “I knew something was going to happen!”

The girls were just as upset as the boys. Nora cried and Peggy tried to comfort her.

“It’s no good telling me they will be all right,” wept Nora. “They must have come down in the middle of Africa somewhere, and goodness knows what might happen. They might be eaten by wild animals, or get lost in the forest or — ”

“Nora, they’ve got food and guns,” said Peggy. “And if the plane has had an accident, well, heaps of people will be looking and searching day and night. Let’s not look on the dark side of things till we know a bit more.”

“I wish we could see the boys,” said Nora, drying her eyes. “I’d like to know what they say.”

“Well, it’s half-term holiday the week-end after next,” said Peggy. “We shall see them then.”

To the children’s great disappointment, there was no news of their parents the next day — nor the next day either. Then, as the days slipped by, and the papers forgot about the lost flyers, and printed other fresher news, the children became more and more worried.

Half-term came, and the four of them went to London, where they were to stay for three days at their parents’ flat. Miss Dimmy, an old friend of theirs, was to look after them for that short time. Prince Paul was to join them that evening. He had to go and see his own people first, in another part of London.

“What’s being done about Dad and Mummy?” asked Mike, feeling glad to see Dimmy, whom they all loved.

“My dear, you mustn’t worry — everything is being done that can possibly be done,” said Dimmy. “Search parties have been sent out all over the district where it is thought that Captain and Mrs. Arnold may have come down. They will soon be found.”

Dimmy took them all to a cinema, and for a while the children forgot their worries. Prince Paul joined them after tea, looking tremendously excited.

“I say, what do you think?” he cried. “My father has sent me the most wonderful birthday present you can think of — guess what it is!”