Taran is the Assistant Pig-Keeper of the oracular pig Hen Wen--a duty which he feels should be noble and meaningful, but instead leads to nothing remotely interesting. He longs to leave his home at Caer Dallben and adventure out into the world, where he imagines a world where heroes like Prince Gwydion keep evil at bay, and peril is never distant.
But when Hen Wen escapes, and Taran follows her, he quickly learns that his dreams of sword-wielding heroism are not quite as he thought. Not only that, but Hen Wen may be in mortal danger--for the Horned King, the latest champion of the nefarious Arawn, is also searching for her as he seeks to rule all of the land of Prydain. And only Hen Wen knows the secret to defeating him.
Now Taran must find Hen Wen before the Horned King--all while avoiding the dark beings sent to find her first. He finds help, too, though: from the hero Gwydion, who is very different from how he imagined him; from Fflewddur Fflam, a bard with a penchant from embellishing the truth; and from Eilonwy, a strong-willed girl who knows a bit about magic. But will it be enough to find Hen Wen in time, and save Prydain?
The Book of Three is one of my enduring fantasy favorites, and when I reread it this summer, I found it just as good as I remembered. Alexander's prose is engrossing, his characters well-defined. Eilonwy in particular I feel the need to bring attention to; although far from perfect, and less so in successive books, she is one of the few female characters in fantasy of this era who has an interesting personality and a life beyond the male characters, although they do invariably stereotype her into the habitual and tight gender roles of this world. The land of Prydain (based on Welsh mythology) is interesting as well; for those who enjoy the inspiration of Welsh mythology in books like Over Sea, Under Stone, this series is particularly recommended. I recommend The Book of Three (and the successive books in the five-volume Chronicles of Prydain) to readers ages ten and up who enjoy high fantasy novels.