The Weirdstone of Brisingamen

The Weirdstone of Brisingamen is a fantasy story for children (but also enjoyed by adults) by the author Alan Garner. It is set in the Wirral of Cheshire and relates the tale of two children, Colin and Susan, holidaying there. The story centres around Susan's bracelet (containing the Weirdstone of the title) which makes the children a target for the forces of evil. The novel borrows extensively from Celtic, Norse and Arthurian legends.

Its sequel is The Moon of Gomrath

A minor point of fact - The Wirral is in West Cheshire, between the Dee and the Mersey. The book is set in East Cheshire, in Alderley and the hills bordering Derbyshire.