A young girl named Luna becomes entangled in a dangerous criminal underworld after witnessing a murder. Luna, a precocious and street-smart adolescent, finds herself under the protection of Serge, a man who navigates the fringes of society. Together, they must evade relentless adversaries while attempting to secure their own survival in a world defined by moral ambiguity and shifting loyalties. The narrative employs a lean, fast-paced style that emphasizes dialogue and immediate action over extensive exposition.

Readers frequently highlight the unique, detached tone that defines Delacorta's writing style. Discussion often centers on the unconventional relationship between the protagonist and her protector, which avoids traditional sentimentality. Critics note the efficiency of the prose, which manages to convey complex tension without unnecessary ornamentation. The book is often praised for its ability to maintain a sense of urgency throughout the narrative. Many readers appreciate the dark, atmospheric depiction of the city that grounds the more improbable elements of the plot.