In Oxford's library, American historian and reluctant witch Diana Bishop unwittingly calls up an ancient magical manuscript, and finds herself confronted by geneticist and vampire Matthew Clairmont, who is determined to get his hands on the book.

Blind to the interest she has stirred amongst creatures, Diana fights an increasing pull towards the magical and turns her back on her witch heritage; matters take an unexpectedly dark turn when Satu is sent by Peter Knox to intimidate her.

Domenico takes Satu's information to menacing vampire Gerbert, who gains the advantage he has been waiting for; Diana refuses to help Knox realize his longing to destroy the vampires and answers his threats with a force of untamed elemental power.

Matthew's hope of keeping Diana safe is short-lived as Ysabeau refuses to welcome the warmblood; Knox calls an emergency meeting of the Congregation to denounce Matthew; Matthew's ferocious brother, Baldwin, plays a careful game to maintain control.

Gillian pays a price for her disloyalty to Diana; the vampires study witch DNA; the fall-out threatens the fragile equilibrium between creatures and the focus is on ending Matthew and Diana's relationship, whatever the cost.