Fitzek masterfully plays with humanity's primal fear of the unknown and helplessness in the air. The claustrophobic atmosphere on the plane, combined with Mats' own fear of flying and psychological pressure from the caller, keeps readers in constant suspense.

Mats confronts his past as a psychiatrist and must face the guilt he feels for his former patient's actions. The novel explores the fine line between wanting to help others and taking responsibility for the consequences.

Throughout the novel, questions arise about who Mats can trust. Is the caller real? Is there more to the story than appears? Fitzek manages to lead readers down false paths and keep them uncertain until the end.