Alexander employs a variety of techniques in this literarily sophisticated series. One of the most effective and pervasive is his skillful blending of mythic and realistic materials. The main episodes in his plot are based on tales from Welsh mythology, especially the Mabinogion. Some of his characters are borrowed from these ancient tales, but others are wholly original creations. On the one hand, on the mythic level one encounters the dark lord of the underworld and meets the fairy folk who inhabit the hollow hills.

On the other, however, one follows the adventures of a young pig-keeper with his friends — a princess, a harpist, and a wild twiggy creature who eludes both categories.

Another successful technique is humor. Even in the moments of danger and tension, a comic tone and perspective lighten the narrative. Much of the humor is in the dialogue, as in the delightfully strained...