The young bard Taliesin comes to the court of King Urien and Queen Morgan. His dream is to make an immortal song about the deeds of King Arthur. His fear is that he was born too late. Arthur is ageing. He uncovers the dark secret of the birth of Morgan's foster-son, Modred. He aches for both, as Morgan tries to bring Arthur and Modred together. But treachery has already been done. The song Taliesin sings may be of Arthur's last battle.