In a quaint suburban town, a single mother named Susan Carpenter navigates life with her two sons, the brilliant 11-year-old Henry and his younger brother, Peter. Henry, an exceptionally intelligent child, has taken on the role of caretaker and financial manager for the family, given Susan's limited resources. He meticulously plans a future for them all, storing his thoughts and detailed strategies in a red notebook. Their peaceful existence is disrupted when Henry discovers that their next-door neighbor, Christina, is suffering in silence under the oppressive and abusive hand of her stepfather, Glenn, who is also a local police commissioner.

Henry meticulously devises a plan to save Christina, documenting every step in his notebook and on cassette recordings. Unfortunately, before he can execute his plan, unforeseen circumstances force Susan to take matters into her own hands. Guided by Henry's notebook and recordings, Susan uncovers the depth of her son's intellect and the severity of the situation next door. Determined to honor Henry's wishes while ensuring their safety, Susan realizes she must act decisively to help Christina, all while trying to reconcile her grief with the responsibilities Henry has left behind.