"Set This House in Order" is a novel by Matt Ruff that explores the complexities of identity and mental illness. The story follows Penny, a young woman who discovers that she has multiple personalities, each with its own distinct traits and memories. As she navigates her life, she learns to understand and integrate these different aspects of herself. The narrative delves into themes of self-acceptance and the challenges of living with a fragmented identity. Through Penny's journey, the book highlights the importance of empathy and understanding in the face of mental health issues, making it a thought-provoking read.