Paris Shin is a celebrated crime novelist known for her "disturbingly realistic" depictions of serial killers. In reality, she is a shut-in suffering from severe agoraphobia, living vicariously through the violence she writes.

When a charming, soft-spoken florist named Joe moves into the apartment across the hall, Paris' frozen world begins to melt. He is kind, attentive, and seemingly perfect. But as Paris starts receiving "gifts" that mirror the murders in her upcoming book-murders she hasn't even published yet-she realizes Joe isn't just a fan. He is a predator who has been watching her through the walls.

The twist? Paris isn't terrified. She's inspired. And she's far more dangerous than he ever anticipated.