On a trip into Wales, Jack tricks a two-headed Welsh giant into slashing his own belly open. King Arthur's son now enters the story and Jack becomes his servant. They spend the night with a three-headed giant and rob him in the morning. In gratitude for having spared his castle, the three-headed giant gives Jack a magic sword, a cap of knowledge, a cloak of invisibility, and shoes of swiftness. On the road, Jack and the Prince meet an enchanted Lady serving Lucifer. Jack breaks the spell with his magic accessories, beheads Lucifer, and the Lady marries the Prince. Jack is rewarded with membership in the Round Table.