Phoebe Harte, 13, is the narrator and protagonist of Mick Harte Was Here. She attends school at the local junior high, which is only a few blocks from her home. Both of her parents work; their family is meticulously organized. At the beginning of the novel, Phoebe loves soccer and playing with her brother, Mick, who is only 10 months younger than her. One day after school, Mick tragically dies in an accident where his bike wheel skids on a rock; he is thrown into the back of a truck and suffers a catastrophic and fatal brain injury.

This changes Phoebe’s life irrevocably. The novel traces Phoebe’s journey through immense grief toward a semblance of closure. Initially, Phoebe is unable and unwilling to process the reality of her brother’s death; she sobs through the night and cannot bear the sight of his bedroom door being closed. She feels isolated from her usually loving and supportive parents, who are struggling with their own all-consuming grief.

Eventually, Phoebe reaches out to her best friend, Zoe, and starts to process her feelings of grief and loss. Phoebe bravely agrees to participate in a school assembly on bicycle safety inspired by Mick’s death.