Fanyüvő is born as the third son of a horse, and he gains his power by suckling the horse's milk. He listens to old tales, mostly about the Forefather and the end of his reign, caused by evil dragons. After the horse's death, Fanyüvő decided to search and destroy the dragons, who seized power over the world. He met his two brothers, Kőmorzsoló and Vasgyúró, who also have superhuman abilities. In search of the Underworld's entrance, they accommodate themselves in a tree hollow. One of them stays there every day, in order to cook mush and make rope while the other two search for the entrance. An ancient and mischievous creature, Hétszűnyű Kapanyányi Monyók keeps asking them to give him some mush. Kőmorzsoló and Vasgyúró refuse to give him food, so Hétszűnyű attacks them and eats the mush from their belly. Fanyüvő, however, stops him by trapping his beard in the tree hollow. Trying to escape, Hétszűnyű fells the tree, and the heroes find the entrance of the Underworld under its roots. Only Fanyüvő dares to go down there, where he finds the three dragons and three princesses. After the victory, Kőmorzsoló and Vasgyúró rescue the princesses but, Fanyüvő puts apples, each containing a castle, into the cauldron, and although both brothers and the princesses try to lift it, it is too heavy for them. The opening closes and Fanyüvő is left down in the Underworld. The desperate Fanyüvő finds a griffin's nest. A snaketries to eat the griffin chicks, but Fanyüvő stops it. To show his gratitude, the Griffin Father takes Fanyüvő to the upper world. The trip is very long so the griffin has to get some food in order to survive. Finally, Fanyüvő has to cut off his own legs to give something to the griffin to eat. After the arrival, the griffin chicks restore Fanyüvő's legs, which gives him more power. He is very angry at his brothers, for he believes they left him behind on purpose, but finally, he forgives them. All three marry with one of the princesses and move into castles, and the Forefather restores the power which he lost by the dragon's arrival.
Production
The film was made from 1979 to 1981. It is the second animated feature-length film of Jankovics.
Comparison with mythology
There are slight differences between Fehérlófia and the film. In Son of the White Mare, Fehérlófia and Fanyűvő are the same person. The film contains elements of creation myths, namely Ősanya, Ősapa, and the Világfa or world tree.
