Tehanu continues the stories of Tenar, the heroine of the second book of the Earthsea series The Tombs of Atuan, and Ged, the hero of the first book, A Wizard of Earthsea.
Tehanu is set almost immediately after the conclusion of the series' third book, The Farthest Shore. Tenar, who arrived on Gont some years ago, married a farmer called Flint and had two children, Apple and Spark. Her husband now dead and her children grown up, Tenar is lonely and uncertain of her own identity. She adopts the child Therru (later to become the Tehanu of the title) after the child is maimed and abused by her natural father.
Later, Ged - once the Archmage, now having lost his powers of wizardry in the supreme effort of closing the hole between the worlds of the living and the dead - returns to the island. He joins the community of Gontish villagers and ultimately marries Tenar. Together, they care for the girl Therru and attempt to protect both her and themselves from her father and the misogynistic wizard Aspen. At the same time, they must search for a place and an identity not only for Tenar and Ged, but for Therru herself. In the end, Therru turns out to be much more than she seems.