The 'Hidden Valley Road: A True Story' focuses on the Galvin family. It tells a complex story of mental illness within the family. It explores how schizophrenia manifested in multiple siblings, and the impact it had on the family as a whole, from the parents trying to cope to the siblings' own relationships with each other.
It's a blend of fact and fiction. While the core idea might have roots in reality, certain aspects of the story have been fictionalized for dramatic effect.