The Secret River is the story of William Thornhill, an Englishman living at the beginning of the nineteenth century whose death sentence is commuted to transportation to Australia. Australia proves brutal to Thornhill and his family, and his relations with the native Aborigines prove bloody and bleak. Thornhill struggles to adapt to his surroundings as his fellow prisoners descend into savagery and brutal, pointless rebellion against the harsh and unforgiving country.
After a childhood of poverty and petty crime in the slums of London, William Thornhill is sentenced to death for stealing wood, however, in 1806 his sentence is changed to transportation to New South Wales for the term of his natural life. With his wife Sal and children in tow, he arrives in a harsh land that feels at first like a death sentence. However, there is a way for the convicts to buy freedom and start afresh.
Away from the infant township of Sydney, up the Hawkesbury River, Thornhill encounters men who have tried to do just that: Blackwood, who is attempting to reconcile himself with the place and its people, and Smasher Sullivan, whose fear of this alien world turns into brutal depravity towards it. As Thornhill and his family stake their claim on a patch of ground by the river, the battle lines between old and new inhabitants are drawn.
The early life of William Thornhill is one of Dickensian poverty, depredation and criminality. Though Thornhill is a loving husband and a good father, his interactions with indigenous inhabitants are villainous. Thornhill dreams of a life of dignity and entitlement, manifested in his desire to own land. After befriending Blackwood under his employ, Thornhill finds a patch of land he believes will meet his needs, but his past comes back to haunt him.
His interactions with the Aboriginal people progress from fearful first encounters to (after careful observation) appreciation. The desire for him to own the land contrasts with his wife wanting to return to England. The clash is one between a group of people desperate for land and another for whom the concept of ownership is bewildering.