Mad Dog Moonlight by Pauline Fisk
Mad Dog Moonlight is only a young boy when he is picked up by the police on a lonely Welsh mountain road with a baby in his arms, and nothing from his past except the memory of the name his mother gave him, and a silver-topped walking cane upon which is engraved a secret word. Fostered by a local family, the Lewises, Mad Dog is renamed 'Ryan', but he struggles to accept this most ordinary of names and families. He longs to find the answer to who he is and what happened to his parents - and so sets off on an extraordinary adventure to uncover the lost secrets in his life. From the streets of Aberystwyth to the lonely hillocks of Plynlimon Mountain, Mad Dog encounters hidden adversaries and unexpected allies in a thrilling journey to discover just who he really is.