A chance encounter with a charismatic fortune teller called Marcus at a psychic fair in Manchester leads Emma Craine into a situation that imperils her soul. For he has a familiar - an incubus which is the reincarnation of Sinistrari, the infamous 17th century Vicar General of Avignon. To maintain his youth, and power over women, Marcus has struck a deal with Sinistrari: every seven years he must mark someone out for him - to do with as he will - and Emma is his latest victim. But in attempting to open Emma's psychic senses he inadvertently awakens her to the power of the Earth Mother. She also finds allies in her sister and her husband and they desperately fight back when the incubus tries to collect on the pledge. Subtle help is also supplied by the enigmatic witches of Pendle who recognise Emma as one of their own, but will it be enough to save her when the demon comes to call for the final time?