Twelve-year-old James lives with his parents and sister. He has a scientific mind and a load of jars, all containing poisons which he has manufactured from plants in the garden - his favourite being Thornapple. When cousin Mirabel and her baby come to stay, James is captivated by Mirabel, who has been rejected by her boyfriend. Mirabel's aunt June, who had also rejected her, suddenly puts her into her good books again, but when June dies, supposedly of gastric complications and leaving Mirabel a large sum of money, James has his doubts as to the true cause of death.
