From then onwards, Matthew thinks he knows a truth about himself: dreadful things happen to the people he loves. It's not a great way to grow up; just as the lonely cottage with a favourite dog and an increasingly dotty grandmother is hardly an exciting alternative to his parents' care. No wonder that an older boy at school, David, becomes Matthew's main man in the business of life-skills - and when Matthew meets David's sister Alison, who is linked to her brother in a closeness that appears more lover-like than fraternal, he feels he's arrived in real life.
The trouble is, the main influence on David's world-view is pharmaceutical. That treachery and glamour dance hand in hand is one of this book's messages: despite David's charisma, being around him somehow always lands Matthew in situations that are awkward, misery-inducing or downright dangerous. As a study in drug psychology, the first part of the book is excellent: characters and readers alike reel under the impact of illegal substances whether they've ingested them or not.
David disappears; searching and grieving, Alison and Matthew become locked in a love-affair whose real pivot is not themselves but David's absence, and a sense of waste and tragedy. It is hard, unhappy and long (rather too long, in the book), but a skilful exposition of how difficult it is to grapple love out of disaster. Set throughout the book against this pain - youthful pain of the kind that is sometimes dreadfully mistaken for something cool and smart - is the picture of Matthew's demented grandmother, trapped alone in her deluded world of regrets and bitterness.
At least, at the end, McDowell offers a gleam of hope. It can be done, he's telling us. You can survive. You might even get happy. His is a moral book, and its moral is perhaps that the only unforgivable thing is to give up on that chance.