Published in 1964, The Book of Three is a high-fantasy adventure novel for middle-grade readers. The first of five books in the series The Chronicles of Prydain, The Book of Three tells the story of Taran, a farm boy who treks with three companions across an ancient kingdom on a mission to inform its rulers of an impending attack by evil forces.

The book won an ALA Notable Book award, and the series won a second Notable Book award, a Newbery Honor, and a Newbery Medal. In 2012, a School Library Journal survey ranked The Book of Three number 18 on a list of all-time best books for children. Its story forms part of the plot for the 1985 animated motion picture The Black Cauldron.

The work contains an author’s note and a pronunciation guide. The 2011 e-book version, based on the 1999 revised edition, forms the basis for this study guide.

Plot Summary

Young Taran dreams of being a great warrior, but he’s a farmhand living in a stronghold just east of the kingdom of Prydain. His foster parent and benefactor, the ancient wizard Dallben, reads to Taran from a tome, The Book of Three, that tells the history of the region. Dallben says the boy isn’t yet ready to learn swordplay or leave the stronghold.

A disturbance among the animals causes the oracular pig Hen Wen to escape. Taran, responsible for the creature, chases after her. He loses her in a forest and stumbles onto a band of mounted warriors led by the Horned King, a vicious warlord who wears a helmet made of a human skull and antlers. The band tries to kill Taran, but he escapes with a shoulder wound. He collapses and sleeps.

Taran wakes to find himself being cared for by the great hero, Prince Gwydion, who knows about Dallben, Hen Wen, and the Horned King. He also knows that Arawn, the evil ruler of the shadowy kingdom of Annuvin, wants to conquer Prydain. The Horned King searches for Hen Wen on behalf of Arawn.

Gwydion and Taran track Hen Wen near the border river, the Great Avren. Along the way, they encounter the cowardly half-man Gurgi, who helps them with their search in hopes of receiving food. They observe the camp of the Horned King’s men and watch as the leader sets fire to prisoners. A war has begun; Gwydion must alert his people.

As they travel, they’re pursued by mounted warriors and the zombie-like Cauldron-Born, dead soldiers re-animated by Arawn for ruthless purposes. The soldiers capture Gwydion and Taran and bring them to the wicked Queen Achren. She offers Gwydion safety in return for his help. He refuses; in a rage, she uses magic to destroy his otherwise unbreakable sword.

Taran is knocked out and cast into the castle dungeon. A girl, Eilonwy, befriends Taran. She doesn’t like the queen, and agrees to help him and his friend escape. She and Taran travel through underground tunnels. They discover an ancient king’s crypt, where Eilonwy obtains a legendary sword, Dyrnwyn. They escape the grounds just as the castle collapses in on itself.

Awaiting them is a fellow escapee, but he’s not Gwydion. He’s a traveling bard, Fflewddur Fflam, who owns a harp with strings that break whenever he tells a lie. Fflewddur was the only other prisoner, and Eilonwy thought he was the man Taran wanted saved.

Taran mourns the loss of Gwydion and decides to fulfill the prince’s quest. Gurgi appears and offers to go with Taran, Eilonwy, and Fflewddur Fflam. The four travel north, hoping to warn Caer Dathyl, home of the good rulers of Prydain, that evil forces march against them. They also seek Hen Wen.

A pair of reanimated dead soldiers on horseback chases them for days but finally gives up. In the process, Gurgi gets injured; his wound rapidly worsens. The four cross a river and enter a region of tall mountains, where they find a beautiful valley controlled by Medwyn, a wizard who protects animals. Medwyn heals Gurgi; the travelers rest and recuperate, then continue on.

While skirting a dark mountain lake, the four are sucked underwater and land in the beautiful subterranean world of the Fair Folk, whose members include little people, winged citizens, and fish people. Hen Wen is hiding in the subterranean world and reunites with Taran. One of the Fair Folk little people, Doli, is assigned to guide them to Caer Dathyl. Doli is an excellent guide but grumpy. He resents being unable to disappear magically like his family members.

Taran’s group cross paths with the Horned King’s forces, and Hen Wen runs away again. The travelers evade the soldiers until the Horned King himself attacks them. Taran tries to draw Dyrnwyn, but it emits a shockwave that knocks him back. The Horned King prepares to kill the boy but suddenly bursts into flames.

Taran wakes in Caer Dathyl. He learns from his friends that the Horned King is dead, his forces routed. Prince Gwydion surprises Taran with a visit. He explains that he wasn’t kept in the Spiral Castle but transferred to a dungeon at the Annuvin stronghold Oeth-Anoeth, where he withstood tortures and learned the secrets of death itself. He traveled north, tracked Taran’s group, found Hen Wen, learned from her the secret name of the Horned King, and killed the evil overlord by uttering his name to his face. He shows Taran Dyrnwyn, which has found its home at Gwydion’s side.

Gwydion gives gifts to each traveler: Fflewddur gets a harp string that will never break; Doli receives the ability to disappear; Eilonwy receives a gold ring with a special jewel carved by the Fair Folk; Gurgi gets a wallet that always contains food; and Taran receives his fondest wish, to return to his home.

Guided by Gwydion, Taran’s group travels to Caer Dallben, where they’re welcomed with a great feast. Taran is glad to be home. He tells Dallben he failed as a hero, but Dallben says Taran led his group well, and that all of them together were heroic. Eilonwy, who’s in fact a royal princess, agrees to stay at Caer Dallben.