This was first published in 1960 and, while it is a children's book, it is well-enough written to grip adults too. The story is set in contemporary Cheshire and features many geographical locations around Alderley Edge and Macclesfield (the author still lives in the area). The plot involves two children (brother and sister) who stay with friendly adults in a farm by Alderley Edge (a large hill and also the name of a nearby village) while their parents are abroad for a few months. The trouble starts when the girl's bracelet is recognised as containing a strange stone – the weirdstone of the title – which has ancient magical significance and has long been missing. This brings all kinds of witches, wizards and non-human denizens of the underworld (literally – Alderley Edge is honeycombed with old mine workings) out into the open to battle for control of the stone in a classic good vs evil contest.
There are Tolkienesque echoes here, but the use of a real setting in the contemporary world, with two normal (if brave and resourceful) children as the heroes gives an entirely different feel. The quality of the writing, fast pacing and relatively short length (236 pages in my paperback edition) make this a story to be devoured in a couple of sessions. Alan Garner was one of the best-regarded children's fantasy authors of the 1960s and it is easy to see why. Highly recommended, and easy to obtain – it was reprinted as recently as 2002. Also available is a sequel – The Moon of Gomrath – which is high on my 'to be read' list.