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 necklace (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.