The book is separated into two main parts, "The First Year" and "The Last Year". It begins shortly before the birth of Tarka in an otter holt on the River Torridge, near the Rolle Canal aqueduct on the Beam estate. After a period learning to swim and hunt, and losing a sibling in a trap, he is separated from his mother and wanders around North Devon alone. His first mate is an elderly otter called Greymuzzle, who is killed during Tarka's first winter, which is unusually harsh. In his second year, he fathers a litter of cubs with his second mate, White-tip. Throughout the book Williamson juxtaposes Tarka with his main enemy, the local otter hunt, and particularly the pied hound Deadlock, "the truest marking-hound in the country of the Two Rivers" (p. 23). The book ends with a climactic nine-hour hunt of Tarka by the pack, and a confrontation between Tarka and Deadlock. Williamson's attitude to the hunt is somewhat ambivalent: while admiring them for their own regard for and knowledge of the otter, and despite being personally friendly with his local hunt, the violence and cruelty of some of his descriptions of hunting is clear.