From the award-winning author of Bestiary, three cousins are forced to complete an impossible and violent task set by a vengeful demon. Cousins Cindy, Yangyang, and Mandy's hot, tedious summer unfolds in their grandmother's hauntingly familiar house. Mandy, the eldest, seeks connection online and exchanges emails with a stranger. Yangyang, the youngest, retreats into her own imagination in search of meaning. But every morning Cindy wakes with strange objects in her mouth: a button, a berry, a coin.

One night, a starved figure with a mouth the size of a needle-tip appears at Cindy's bedside. She is hunger-afflicted, a demon with no descendants to feed from: she is Needlemouth. Part vampire, part hungry ghost, Needlemouth forces the girls into a grim task to end a man's life.

Cindy, Yangyang, and Mindy are plunged in and out of the demon realm, where they are called to break out of the indifference and numbness of their claustrophobic worlds, and where they are met with the most rageful and resistant parts of themselves. In a quest to satisfy the demon's hunger, they unravel their shared grief and reckon with the cyclical violence that shaped their family. For readers of Akwaeke Emezi and Carmen Maria Machado, K-Ming Chang has crafted a reimagined coming of age novel that asks: what does it mean to become the monster instead of slaying it?