"What was that? "said Jacob quickly.

"A big plane. Right over here."

"Practically knocked our heads off," added Dickie.

Then Jacob seemed to make up his mind. He put his hands up to his mouth and hooted, and the answer came back to him at once from higher up the wood. Then he turned and looked oddly at the children. "Come," he said. "We will go and find this bird," and he led the way uphill through the trees. Twice again he called, and twice came the answer through the fog. And as they toiled uphill he talked loudly to the twins, almost as if he wished their voices to be heard.

Then came a new voice from just in front of them.

"Help!" someone was calling. "This way, please, whoever you are. Where are you?"

And so they found the owl - the mysterious bird in his nest. Under a rock a white-faced man in a raincoat was lying. He was young and pleasant looking, and smiled when he saw them. One foot was stretched out awkwardly, but the twins' eyes opened wide in amazement when they saw beside him, half-trailing from a tree, a muddle of strings, straps and billowing silver-grey material. Before they could speak he said: "Hello! Did you hear me call? Was it one of you hooting like an owl?"

"Yes," said Jacob quickly. "I hoot like an owl. These children - they are lost in the mist and I find them. You have hurt yourself?"

The stranger nodded. "Ankle twisted. Rather painful. I suppose I'd better tell you who I am. I bet you'd like to know, wouldn't you, young man?" he added, turning to Dickie.

"Yes - we would," Mary answered shortly.

The man looked at her and grinned.

"Is that place your home?" the man asked.

"Oh, no! That's where Mrs. Thurston lives."

"I see. D'you think she'd look after me till I get this ankle right?"

"Now I know what that is," Dickie broke in excitedly. "It's a parachute! You've fallen out of a plane."

"You're right, son. That's just what I've done, and now I've got to let you into my secret, but you must promise faithfully not to tell anyone. Do you both promise?"

"We swear," said Mary solemnly.

"Very well. I'm a British officer, and it's one of my jobs to test parachutes in all kinds of weather."

"It's a funny thing," said Dickie thoughtfully, "but we're always finding people."

"What do you mean?" Jacob asked shortly.

"Well, there was a man we trailed the other day up on the mountain. And then just this morning we found John Davies in a secret place, and this afternoon somebody was runnin' about in the woods down by the house. There's always people about this place."

"And owls," added Mary.