The Stolen Bride — Tony Hays

Malgwyn ap Cuneglas is counselor to Arthur, High King of the Britons. When he accompanies his liege to the West to broker a deal between warring tribes they come across a scene of utmost depravity and murder to sicken even the most battle-hardened warrior. Things don't get any better when they finally arrive at their destination to discover that King Doged is fighting to keep his kingdom safe from both Saxons from abroad and younger nobles vying for power. Doged loses that fight when shortly after Arthur and his counselor arrive, he is murdered. His young wife, defenseless and alone, appeals to Arthur to find her husband's killer. Arthur quickly agrees and Malgwyn is given this almost impossible task.

Why would Arthur be so interested in helping keep this small region stable and under the High King influence? Perhaps because Doged's people had discovered caves that might contain huge veins of gold....