Cal has spent an utterly miserable childhood in Bangor with his mother who is schizophrenic and an alcoholic. Since he was six he has looked after her and run the house. Now he is old enough to leave home and get a job, he is off like a shot and the story opens as he travels down to South Wales by train to live with and work for his uncle Trevor who runs an accountancy firm. On the way he falls asleep and gets of at the wrong station, Corbenic, where he is directed to the Castle Hotel. He is greeted by the wheelchair-bound host, Bron, and treated to a sumptuous banquet at the end of which he witnesses the Grail procession. He fails to ask the question, believing it all to be an hallucination and fearing he is losing his mind as his mother has. Next morning, he wakes in a ruin with only a sword that Bron has left him to indicate that his experiences have been real...
There are various versions of the Grail legend and Fisher has based her book on the Welsh versions (naturally) as well as those by Chrėtien de Troyes and Wolfram von Eschenbach. Hence Cal is Percival and not Gawain or Galahad who are the Grail Knights in other versions. Those who are interested in such things can trace the parallels, but it is not necessary for the appreciation of this powerful story.
As ever it is beautifully written with a terrific sense of place and although the characters have their roots in their legendary counterparts, they are real people with real flaws and problems.
Young readers, 12 plus I would say, (though as with Philip Pullman some mature 10 or 11 year olds too) will love it, but as the other reviewers have said it's for adults too. A great read!