A simple job turns deadly when novice detective Mary Wandwalker is hired to chaperone Rhiannon to the Oxford University Summer School on ancient Celts. Concerned by rhetoric surrounding blood sacrifice, Mary and her operatives, Caroline and Anna, attend a ritual at a sacred well. They uncover a disturbing truth: those who fail to individuate their gods risk being possessed by them. The Reborn Celts, who run the summer school, are infiltrated by white supremacists, raising the question of whether their immersion in myth signifies psychic wholeness or hints at their intent for terrorist violence. Mary, posing as a harmless woman, agrees to spy on the group but is horrified to discover Anna's affair with chief suspect Joe Griffith, who is also Rhiannon's obsession. As Mary realizes the Reborn Celts' deadly intentions, she becomes entangled in three rites to summon their gods: at an Oxford well, by the Thames, and in Celtic London, where bloodshed aims to restore a 'lost river.' Before the summer solstice, Caroline and Anna race to save Mary, who has been kidnapped. Will she become the crone sacrifice, or can the three women reconstitute their detective family, embodying archetypal feminine compassion?
