Victory in the North is sealed. The High King and his greatest ally, Kerin Brightspear, returen home in triumph with the women they love. Summer stretches ahead with its promise of uncomplicated happiness. But their fragile peace is shattered on Midsummer's Eve, when Vortigern's rivals proclaim his oldest son Rufus as king, firing a brutal civil war. Kerin, now known to all as 'the King's Right Arm', rallies old friends and new allies as Rufus draws a huge force of fanatics and mercenaries to his stronghold in Glevum. Determined to oust his father and destroy what he sees as the forces of heresy and evil, Rufus boasts of weapons which his enemies cannot hope to withstand. But Vortigern's warriors have a scret weapon of their own; a thing of mystic power, concealed for centuries by the druids. They have the Carnyx. Kerin alone believes that the ancient war horn could still strike terror into an enemy. But if he is wrong, the kingdom and all he loves could soon lie in ruins as Vortigern and his son face thie final battle.