When a human skeleton, with an animal skull instead of a head, turns up in Copenhagen, investigator Christian Porsing is immediately drawn into the case, but there are no clues to go on.

By chance, Sigga Freitag, the former star profiler of the German police, is in Copenhagen and he impulsively decides to seek her out to get her assessment of the case. But Sigga, with her complicated background, is not the easiest to work with.

When yet another animal-headed skeleton appears, they realize that the skeletons are only the beginning of a case far more sinister and macabre than they have ever seen before.