When Gerraent's sworn friend, Blaen of the Boar clan, discovers the incestuous relationship, Gerraent kills him. Gerraent is in turn killed by Blaen's brother. Nevyn takes Brangwen away from the Falcon lands, but the distraught girl drowns herself. Overwhelmed by guilt and grief, Nevyn rashly swears an oath that he will not rest until he sets things right. Thunder booms from a clear sky – a sign that his oath has been accepted by the Great Ones (transcendent spiritual beings similar to Bodhisattvas).