Lewis and Hathaway are called in to investigate the death of Reuben Beatty who works at the University of Oxford’s Department of Psychology. He has been discovered dead injected by etorphine, a paralysing agent in the offices of psychic ‘Randolph James’.

Lewis and Hobson are examining the body of murdered Vicki Walmsley when a theft of etorphine is reported by the Garsington Equine Centre. The drug was last used a year earlier on a horse that injured its teenage rider, Joshua Grace – the brother-in-law of Reuben Beatty, the first murder victim.