Peter knew how the mountain mist came suddenly like this to these hills and valleys. Once she had been caught in just such a mist with her father, and last summer, of course, the twins had been lost too. Even as she looked back, the hard outline of the Chair wavered and disappeared. Then the atmosphere became cold and clammy as the fog swirled round them. Suddenly Jenny gave a stifled little scream and pointed up the track which led to the mines. Shadowy in the thickening mist, the two girls seemed to see a figure on horseback waving ghostly arms but no sound of hooves came to their straining ears. Then, far away on the hilltop, it seemed to Peter that tiny, gnome-like figures flitted in uncanny procession.

Jenny turned and wailed into Peter's shoulder.

"Peter. It's true. It's them. They're riding again. What shall we do, Peter? We must hide our eyes. We mustn't even see them. Don't look, Peter."

Even Peter wavered a moment at this outburst, but before she could recover herself, a new sound came to them through the mist. Somewhere from over their heads, the silence was broken by a weird, throbbing hum. The thickening air vibrated as the sound increased and, as Jenny cowered in terror at her feet, Peter, looking up, saw a gigantic black, shadowy bulk rushing over their heads.

4. The Lone Piners Join Up

Three days after Peter had made her adventurous journey to Seven Gates, her friends, only a few miles away, were wishing she was with them, as they toiled slowly up towards the famous Lone Pine Camp for the first meeting of the Club since the Christmas holidays.

There were four in the party. First came David, nearly sixteen now, wearing jeans and a sweater and carrying a laden haversack. He tramped on steadily without taking any notice of the petulant duet behind him, as the twins, Richard and Mary, rather breathless and hand in hand, strove desperately to keep up with his long strides. They were absurdly alike, and today both were wearing blue shorts, yellow shirts, grey socks and brown anoraks. Perhaps it was Mary's curls that made her seem to be a fraction taller than her twin.

The fourth member was a black Scottie dog called Macbeth, whose affection for Mary was only equalled by Mary's loyalty to her twin.

"I don't suppose you're really interested to know what we think..." Dickie was saying as David jumped a stream without even looking back at them.

"'Course he's not interested," Mary continued. "'Course he isn't. He's just a selfish old beast hidin' the letter and not letting us see."

"It's always the same, twin," complained Dickie. "No 'sideration for others... David! Why do you go so fast? You know Mary and me can't cross this foamin' torrent without a... a... a canoe or something."

"I know why it is, Dickie. He's afraid we'll see what Peter's written."

"Yes. He just thinks she's his friend."