The Black Cauldron ( in a summary ), is the story of an Assistant Pig-Keeper named Taran who lives on a small farm with an old wizard, Dallben. Taran greatly wants to became a warrior, but all he is allowed to do is take care of Dallben's pig, Hen Wen.
One day, while Taran is bathing Hen Wen, the pig starts to act funny. Dallben hears the commotion and tells Taran to bring her inside. Dallben then tells Taran that Hen is magical and can tell the future. Dallben uses Hen's power to tell whats the matter: the Horned King is in Prydain and is looking for a legendary weapon called the Black Cauldron. The Horned King knows that Hen Wen is able to help him find that. So Dallben tells Taran to take Hen to a hidden cottage in the forest and stay there.
Taran on the way, loses Hen Wen, and meets a furry creature called Gurgi. Gurgi wants his food, but Taran won't let him have it. Taran then hears Hen, and is in time to see her carried off to the Horned Kings Castle buy the King's gwythaints.
Taran goes to the castle and frees Hen, but he is caught and thrown into the dungeon. A Princess, Eilonwy, breaks into his cell via an underground passage and offers to help Taran. They come across a burial chamber when walking and exploring the underground passages. Taran finds a sword in the chamber and takes it. The pair then come across a minstrel, Fflewddur Fflam, who was recently thrown into the dungeon. Taran and Eilonwy free him. Taran gets separated from the princess and the bard, and runs into a guard. Trying to protect himself, he discovers the sword he took is magic. Using the sword the trio makes their escape.
When the escape is reported to the Horned King. He is pleased. Who, the King points out, is better to find the pig than the pig-keeper himself? So the guards send out the gwythaints to follow them.
The trio find a nice clearing in the forest to rest in. Taran boasts about his bravery about saving the princess and Fflewddur. Eilonwy disagrees, saying it was the magic sword. The two quarrel, and end up walking away from each other in anger. Fflewddur calls to them, reminding them that they must work together. Taran eventually feels guilty, so he goes to find Eilonwy to apologize. He finds her leaning on a willow tree, crying. Taran and Eilonwy make up, only to hear Fflewddur screaming bloody-murder. Gurgi has found the bard, and is depriving him of all his wordly possesions. Taran shows up, Gurgi immediately stops harassing Fflewddur and tells Taran that "old man, uh, fall down!". Gurgi sees Eilonwy, who, in her opinion is quite charming. Taran tells Gurgi to leave, but Gurgi remembers that he saw Hen's tracks. He leads the trio to the trail.
They follow the tracks, only to find that they lead straight into a pond. Gurgi starts to cross it on stepping stones, to find that he has triggered a whirlpool. Gurgi cries for help, and Taran, while trying to rescure Gurgi, is pulled in too. Eilonwy and Fflewddur are pulled in trying to save Taran and Gurgi. They are pulled under the pond into the world of the Fair Folk. Some smaller Fair Folk watch the companions in awe, they giggle about the fact that Doli's whirlpool is broken, once again. King Eidilleg arrives on the scene, and looks at the repair job Doli has done on the whirlpool. The companion have found them and Eidilleg, who is quite shocked, explains who they are and if they can be of any service. Doli bursts out in rage and he carries on about a pig being sucked into the whirlpool too! Taran realizes it's Hen Wen, and they are reunited.
Eidilleg learns about their quest, and says Doli can direct them to the Marshes of Morva, where the Cauldron is. Taran wants to beat the Horned King to the Cauldron and destroy it before he can use it. So Eidilleg tells Doli to guide them and the troop sets out.
The Marshes of Morva is a dreary, dreadful place. Eilonwy feels that they are lost. When climbing a small hill, Fflewddur and Doli fall off the edge, and stumble upon a hut. The group look around ouside. It appears no one is home.
Taran pushes in the door, and they enter. Eilonwy checks in the drawers, Taran the cubards, Gurgi the closets for the Black Cauldron. When opening a chest, Taran releases a myraid of frogs. Eilonwy screams, and Doli explains that those frogs were once human, transformed by the witches. Gurgi jumps on Taran saying that he has found the Cauldron. He leads him into a large room full of cauldrons.
Then, a witches cackle is heard, and the crew realizes that they have been found by the witches. Orddu, the oldest witch, tells them that they "will all be turned into frogs and eaten"! Orgoch, tried to take a bite out of Taran's arm, but he's too quick. Fflewddur tries to make his exit, but Orwen grabs him, admiring his "good looks". Fflewddur is appalled, but tells her she is quite attractive, for fear of his life. Orgoch wants to eat, so she turns Fflewddur into a frog, and tried to catch him. Orwen saves him, and pulls him close and hugs him. Orgoch turns him into a frog again, and Fflewddur is trapped in Orwen's clevage. Orwen finally finds him, and turns him human, once again.
Taran draws the magic sword and asks for the Black Cauldron. The witches are distressed, because they haven't been asked for it in two thousand years. Orddu tries to confuse Taran and sends swarm of cooking utensils at him, asking if he'd prefer any of those. The magic sword stars to magically cut through the utensils, which impresses Orddu quite a bit. She tells her sisters they'll trade the Cauldron for the sword. Orddu informs the crew that she'll trade, but for the sword only.
Taran gives it up reluctantly. The witches take the sword and dissappear. They hut is torn away in a violent wind, and the crew is left in the marshes, where the Black Cauldron pushes itseld out of the dirt.
The Black Cauldron stands before them! Taran approaches it as the three witches appear in the clouds, laughing at them. Orddu tells them mockingly that the Cauldron cannot be destroyed. This erupts into a discussion, about how the Cauldron can be destroyed. "Now listen carefully, the Black Cauldron cannot be destroyed. Only it's evil powers can be stopped....a living being must climb into it on it's own free will....but that poor little duckling will never come out again alive" Orddu tells them, as she and Orwen and Orgoch disappear. Gurgi almost jumped into the Cauldron, but decides not to when he hears the consiquences.
The group sits around a fire, brooding about their problem. Doli gets up angerily and says that humans screw up everything ang he disappears and goes home. Taran agrees with him, calling himself a failure. Eilonwy protests and says he must believe in himself...cause she does! Taran is momentarily happy to hear this, but Eilonwy sudden't points out a gwythaint. Taran, Fflewddur and Eilonwy rush to hide the Cauldron...while Gurgi runs away from the danger. Soon the trio is surrounded and captured by Henchmen, while Gurgi watches from a distance.