When Lena's younger sister Fressa is found dead, their whole Viking clan mourns—but it is Lena alone who never recovers. Fressa is the sister that should've lived, and Lena cannot rest until she knows exactly what killed Fressa and why—and how to bring her back. She strikes a dark deal with Hela, the Norse goddess of death, and begins a new double life to save her sister.

But as Lena gets closer to bringing Fressa back, she dredges up dangerous discoveries about her own family and finds herself in the middle of a devastating plan to spur Ragnarök –a deadly chain of events leading to total world destruction. Still, with her sister's life in the balance, Lena is willing to risk it all. She's even willing to kill. How far will she go before the darkness consumes her?