"Time we had another adventure," Peter tells David one day. And almost before the words are out of his mouth, the adventure has begun. Mr and Mrs Morton are suddenly called away to London, they expect to leave the children in the hands of Agnes, their housekeeper. But Agnes has been called away - to look after her sister's guest-house in Clun, a village in the Welsh border country. So what will happen to the children? It's Mary and Dickie, the Morton twins, who find the solution. They will all go with Agnes and stay in the guest-house. Not just David and the twins, but all the members of the Lone Pine Club, including Jon and Penny Warrender from Rye. The children soon discover that there is a sheep-stealing gang in the district, but who are they? And what is going on at Grey Walls, the strange old house standing on Offa's Dyke? As lively and resourceful as ever the Lone Piners are soon caught up in this new mystery, trailing the sheep and the thieves, and unravelling the secret of Grey Walls.

ISBN: 0 903445 88 3
178pp Hardback
Our RRP £6.95