Anna Owens, a recently widowed young mother who accepts employment as the governess for King Mongkut of Siam (Rex Harrison). In Siam, she finds that her highly intelligent employer is also a backward tyrant with a childlike temperament. Using her strength of will and getting help from the king's first wife, Lady Thiang (Gale Sondergaaard), Anna tries to transform the king and educate his children while also preserving her own dignity.