Go Seo-in, the illegitimate daughter of a royal physician, is driven to the brink of death by her father and then rescued by the Wolf King, Sim Nan-chang. After spending a single night together, she is exiled for her family's crimes and raises her son, Go An-yeong, alone—a boy who can understand the speech of beasts. Five years later, while searching for herbs to cure her son's illness, she reunites with Sim Nan-chang, but neither recognizes the other. When An-yeong is branded a monster for speaking with animals, Sim Nan-chang appears, protects mother and child, publicly acknowledges his paternity, and clears up a long-standing misunderstanding. Together they overcome countless trials—her stepmother's revenge, conflicts among the wolf clan, and a fox spirit's schemes—until she becomes pregnant with twins, and the family of three finally lives in complete happiness together.