Vic Wood's ordinary life crumbles when her younger brother is accepted into the Acheron Order, a secret society of witches tasked with keeping the world of the dead at bay. While Henry inherited their absent mother's magical abilities, Vic did not. So she is stunned when the Order's mysterious leader invites her to join the other initiates at Avalon Castle, to prove his controversial hypothesis - that magic can be taught.

But outsiders aren't welcome at Avalon, and Vic has to fight for the chance to stay. Scouring archives and libraries for anything she can use to her advantage, Vic uncovers a dangerous truth- the Order is on the brink of war, and her own mother might have started it.

And then there is Xan, the Order's imposing, ruthless, frustrating head Sentinel. Xan makes no secret that he wants Vic gone. But even the cavernous castle can feel cramped and claustrophobic amidst their electric connection . . .

As simmering tension gives way to violence, Vic must choose whether to leave the preternatural behind, and risk losing her family, or stay, and remain powerless in a world where power is everything.