The Summoning. The Seventh House, #2

A fast-moving Gothic thriller, sinister, sexy and evocative, calling on many elements of the supernatural as well as contemporary issues, as experienced through the eyes of a feisty heroine without a recorded identity. Ankerita, a Tudor noblewoman released from her tomb after half a millennium of disturbed sleep, is desperately trying to stay one step ahead of traffickers, the evil organisation that needs her for her blood, and the demons still trying to reclaim her soul.
She becomes aware that her best friend is dying, but that there is a chance the friend can be cured if Ankerita can complete the 'Summoning'. She needs to track down a number of lost treasures, hidden long ago by a sorcerer from Celtic legend. The ritual shall be evoked on a specific night when five planets align again for the first time since she died, but her pursuers are ever present, and if the invocation is disturbed, it will be Ankerita who loses her life.
As per 'Ankerita, Seasons out of Time', the first novel in this series, all supernatural content is based on existing sightings, legends etc., some of which have been experienced by the author personally, and the occult procedures are a combination of documented rituals and methods.