Mira is a desperate young woman, hired by a wealthy single mother to tutor her lonesome son, Yuchan. But Mira is not who she presents herself to be; she is haunted by the death of her own family and motivated by the dark pulse of vengeance. Yuchan was cruel to Mira's mother. A kind of cruelty she can't ever forgive.

And then there is Jiwon, the boy's mother, a bad mother, Mira thinks--or so Jiwon tells herself she must not be.

But as Mira spends more time in the family's sprawling home, she begins to suspect Yuchan is not the culprit she's after. Someone else in the family has been pulling the strings. Someone with a deviant plan she can't begin to imagine.

Structured around four different letters and journal entries: Mira's, Jiwon's reply, Yuchan's younger brother's diary entry and, finally, Mira's own written recollection. Each new section brings us deeper into a web of cruelty, consequence, and closer to the truth.