Jacqueline is a good girl - the sort that always gets merits in school and is no trouble to anyone. Her parents' business keeps them very busy, and while they are loving, they have little time for her. Every school holiday she stays with her grandma in Camden. That is where the trouble starts. In an old cupboard in grandma's attic, Jacqueline comes across a bottle with a sticky substance in it. One sniff and she becomes Jacqueline the bad. The chain of events this starts is horrifying; and along with her bad behaviour, Jacqueline starts having terrible nightmares - dreams that parallel Stevenson's story of Jekyll and Hyde. Jacqueline has never read the story, but she realises there are awful things happening to her, so she gets rid of the bottle. However, she has lost control, and sometimes Jacqueline the bad takes over anyway. When she finally sets fire to the school, she is sent to a 'place where people listen'. In fact, the whole story is told in the first person, and only at the end does one realise she is talking to a psychiatrist. Jacqueline is surrounded by people who care deeply for her - her grandma particularly - and there is great hope she will get over her split personality though there is some suggestion of schizophrenia. Jacqueline has always known there was a bad half lurking under the good, and one isn't sure whether the sniffing is a cause or a catalyst. A gripping and important book.