The frame story tells that Madog sends Rhonabwy and two companions to find the prince's rebellious brother Iorwerth. One night during the pursuit they seek shelter with Heilyn the Red, but find his longhouse filthy and his beds full of fleas. Lying down on a yellow ox-skin, Rhonabwy experiences a dream of Arthur and his time. Serving as his guide is one of Arthur's followers, Iddawg the Churn of Britain, so called because he sparked the Battle of Camlann when he distorted the king's messages of peace he was supposed to deliver to the enemy Medrawd. Iddawg introduces Rhonabwy and his friends to Arthur, who regrets that Wales has been inherited by such tiny men. Iddawg reveals that Arthur's men are assembled to meet theSaxons at the Battle of Mount Badon. However, Arthur is more concerned with a game of gwyddbwyll he is playing against his follower Owain mab Urien. While they play, messengers arrive declaring that Arthur's squires are attacking Owain's ravens; when Owain asks that this be stopped Arthur only responds, "your move". Finally Owain orders his ravens to attack Arthur's servants; when Arthur asks him to call them off, Owain says "your move, lord". Eventually Arthur crushes the chess pieces into dust, and the two declare peace between their forces. After this the Saxons send a contingent asking for a truce, which Arthur grants after consulting his advisors. Cai declares that any who wish to follow Arthur should come to Cornwall. The noise of the troops moving wakes Rhonabwy, who realizes he has slept for three days.
Interpretation
There is no consensus about the ultimate meaning of The Dream of Rhonabwy. On one hand it derides Madoc's time, which is critically compared to the illustrious Arthurian age. However, Arthur's time is portrayed as illogical and silly, leading to suggestions that this is a satire on both contemporary times and the myth of a heroic age. Rhonabwy is the most literary of the medieval Welsh prose tales; it may have also been the last written. A colophon at the end declares that no one is able to recite the work in full without a book, the level of detail being too much for the memory to handle. The comment suggests the work was not popular with storytellers, though this was more likely due to its position as a literary tale rather than a traditional one.