Catherine Fisher's Corbenic is part of Red Fox's Definitions series, which also includes Jonathan Stroud's The Leap, and like The Leap, Corbenic can be read on two levels, but I'll talk about that later.
Corbenic is based on Chrétien de Troyes' Perceval, le Conte du Graal, in which Perceval meets the crippled Fisher King and sees the Holy Grail, but fails to ask the question that would heal the injured monarch. When he learns of his mistake, Perceval vows to find the Grail castle again and fulfill his quest. In a similar way, Cal is on his way from his home in Bangor by train to Chepstow where he's going to live with his uncle Trevor and work in his accountancy firm. Cal's father left home when Cal was two and his mother has schizophrenia and a drink problem so Cal has been bringing himself up since he was 6. As the train is making its way to Chepstow Cal falls asleep and when he wakes suddenly at a station, he thinks he heard the guard say they were at Chepstow. He jumps off the train and it pulls away before he discovers his mistake. He is at Corbenic station. He waits some time for another train then decides to look for a phone instead. Walking along a dark lane he sees two men fishing on a lake and one of them tells Cal that there is a hotel about a mile down the road. Cal finds the hotel, a luxurious affair that must have at least 4 stars, and is surprised when he's told that a room for the night will be free. Cal rings Trevor to tell him where he is, then showers and dresses for dinner. Dinner is a sumptuous affair, more of a banquet than an ordinary meal and Cal feels as if he's strayed onto a film set. He is introduced to Bron, one of the two men who were in the fishing boat, who is wheelchair bound and apparently in great pain. Cal eats heartily then Bron talks to him, asking questions about his family. Bron urges Cal to go back home, but Cal refuses, then a strange procession takes place. Bron tells Cal that he must look at the Grail, which is coming, and see it then help them. Cal sees a bleeding spear, two golden candlesticks and then a dented golden cup which shines fiercely, carried across the dining room. However, he tells Bron that he has not seen it, believing himself to be affected by the unaccustomed wine he drinks during the meal. When Cal wakes the next morning, the castle is a ruin and there is a sword through his pillow, a parting gift from Bron.
Cal arrives in Chepstow and does his best to settle into his new life, in spite of boredom and his mother's phone calls begging him to come back home. One day he takes the sword to work, intending to take it to an antique shop to sell, but on the way to the shop, Cal is set upon by muggers, and finds himself trying to use the sword to defend himself. He is injured but picked up by a man and a girl who calls themselves Hawk and Shadow respectively. They are part of an historical re-enactment group in which Cal gets involved when he learns sword fighting from Hawk. The group is led by a man named Arthur, who has a foster brother named Kai. Also in the group is an old man who is referred to as The Hermit but calls himself Merlin.
Cal promises his uncle and his mother that he'll go home for Christmas since Trevor and his girl friend are going away, but Cal chickens out and stays in Chepstow so he can take part in a mediaeval festival on Christmas Eve. He rings his mother and tells her that he'll go home for the New Year instead, but before Christmas Eve is out, Cal is told that his mother is dead of an overdose. It's unclear whether she deliberately killed herself or whether she was too drunk to realise she had already taken her pills. Cal and Trevor go to Bangor for the inquest and funeral, and to sell the house and its contents, then Cal tells Trevor he wants to stay on for a few days. In fact, he's not going to stay in Bangor but go in search of Corbenic. He encounters Merlin in his wanderings, who tells him he's been away for more than 3 days, but it's only when he visits Sophie (Shadow), who has left Arthur's group and gone back to her home in Bath after Cal turns her in (since she had run away from home), that he discovers he's been gone for 3 months and Trevor has been worried sick about him, as have Arthur's group. Cal sets off to look for Corbenic in Glastonbury, following a tip of Merlin's. He finds it and is able to drink from the Grail, healing himself and Bron, and the land, and he is able to make peace with his mother who is the Grail bearer.
This book can be read on two levels. On one level Cal is an unhappy teenager suffering guilt over leaving his mother to deal with her illness and his experience of Corbenic is illusion, delusion or hallucination. At another level, however, Cal's experiences are real and he's a reincarnation of Perceval, who helps to find the Grail and heal the Fisher King.