The Hounds of Sunset — Edith Pargeter

Powerful Prince Llewelyn still treasures his vision of a Wales united against the threat of the English kings. The dream seems near fulfilment until Edward, vigorous, ambitious, and arrogant, takes old Henry's place on the English throne -- and more than his share of power. Trouble also looms nearer home, where the youngest of the Welsh brothers, David -- blue-eyed, charming, and deadly -- is plotting Llewelyn's downfall. Threatened on all sides, Llewelyn looks for comfort from the beautiful Eleanor de Montfort, the jewel in his crown and the only shining star as night falls on his dreams of power.