When a mysterious magical infection begins granting unstable, destructive powers to ordinary citizens, Skulduggery Pleasant and Valkyrie Cain must intervene to prevent total societal collapse. As the Sanctuary struggles to contain the outbreak, a group of teenagers led by the corrupted Kitana discovers their newfound abilities and begins a campaign of chaos across the city. Valkyrie and Skulduggery face the dual challenge of managing the public panic while confronting these volatile, god-like adversaries. The narrative maintains the series' characteristic blend of sharp dialogue and high-stakes supernatural combat, presented through a third-person perspective that tracks multiple shifting threats.

This installment is widely regarded as a pivotal shift in the series, moving toward darker, more complex thematic territory as the stakes for the protagonists escalate. Readers often highlight the author's ability to balance the signature humor of the earlier books with the increasingly grim consequences of the characters' actions. The introduction of the infected teenagers serves as a catalyst for significant internal conflict, forcing the leads to confront the moral ambiguity of their roles as protectors. The pacing is frequently praised for its relentless momentum, ensuring that the tension remains high from the opening chapters through the final confrontation. The work reinforces the series' reputation for blending lighthearted wit with genuine peril in a way that keeps the narrative trajectory unpredictable.