Returning to Fernandina Beach to settle his late father's affairs, Jake Forrest uncovers cherished reminders of two early 1970's summers, an era punctuated by the ongoing turmoil of the Vietnam War and the effects of civil rights legislation. Against this setting teenage Jake and his friend Rory Perkins build a raft to explore the salt marsh, pursuing big fish and adventure. The boys navigate into uncharted latitudes including a friendship with a mysterious older black man, Amos George, which garners the attention of the town's bigoted sheriff. A savage storm uncovers the secret of forgotten smugglers' treasure, but also unhinges Jake's grieving mother who fears she's lost another son. The boy's efforts to salvage the treasure garners the attention of the local menacing tyrant, setting in motion a confrontation with grave implications for the boys and Amos George.