In Oxford’s Bodleian library, brilliant American historian and reluctant witch Diana Bishop unwittingly calls up an ancient magical manuscript, Ashmole 782, which has been missing for centuries and finds herself confronted by acclaimed 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, but matters take an unexpectedly dark turn when Satu is sent by Peter Knox to intimidate her.

Domenico takes information he’s extracted from Satu to menacing vampire Gerbert, who gains the advantage he has been waiting for. After sending Juliette into the world to do his bidding, Gerbert consults with Meridiana, the witch whom he keeps in thrall, but what does the prophecy she delivers mean?

Matthew’s hope of keeping Diana safe at Sept-Tours appears short-lived as Ysabeau refuses to welcome the warmblood under her roof.

Gillian pays a heavy price for her disloyalty to Diana, but not before news that vampires are studying witch DNA reaches Knox. The fall-out threatens the fragile equilibrium between creatures and the focus is on ending Matthew and Diana’s relationship whatever the cost.

Satu brutally tortures Diana in Gerbert’s isolated castle ruins. Matthew, now sworn to hunt down and kill anyone who tries to harm Diana, attempts a daring airborne rescue mission with Baldwin in tow, but they are too late to prevent Satu invoking dark magic in a bid to open up Diana and see the magic inside her.

After confronting her aunts, Diana learns the tragic circumstances surrounding why she was spellbound as a child.

Matthew’s attempt to rescue Diana from Juliette goes horribly wrong and Diana finally discovers just how lethal her magical powers can be. As Matthew lies dying, Diana must strike a dreadful bargain with the goddess and make the ultimate sacrificial pact with enduring consequences.