Mrs Mannering thinks that a peaceful holiday in the Welsh mountains couldn't possibly land the children in another dangerous adventure. How wrong she is! Philip, Dinah, Lucy-Ann and Jack are soon up to their necks in the mystery of a rumbling mountain, roaming wolves, and a mad genius who plans to rule the world. Other titles in the Adventure series: The Island of Adventure The Castle of Adventure The Valley of Adventure The Sea of Adventure The Ship of Adventure The Circus of Adventure The River of Adventure