This section is from the book "Myths And Folk-Tales Of The Russians, Western Slavs, And Magyars", by Jeremiah Curtin. Also available from Amazon: Myths and Folk-Tales of the Russians, Western Slavs, and the Magyars.
Mirko ran down straightway to see how much his strength had increased. He picked up the club, whirled it around his head, and let it go so that it came down just in front of Doghead. Doghead's horse stumbled over the club, whereupon his master flew into a rage, and cried out: "May the wolves and dogs devour thee! Seven hundred years have I ridden thee, and to this day thou hast never stumbled. Why begin now?"
"Oh, dear master," answered the magic steed, "there is mighty trouble at home; for the club which thou hast sent ahead has been hurled back, and I stumbled over it".
"Oh, that's nothing!" said Doghead. "Seven hundred years ago I saw in a dream that I should have a struggle with Mirko, the king's son, some day. He is now at the castle; but what is he to me? There is more strength in my little finger than in his whole body." With that Doghead sped homeward and was soon there.
Mirko, the king's son, was waiting in the courtyard, and when Doghead saw the prince he made straight towards him and said: "Mirko, I know that thou art waiting for me. Well, here I am; what dost thou wish, that we should fight with swords or wrestle?"
"I care not," answered Mirko; "any way that may please thee".
"Well, let us try it first with swords," said Doghead.
He got off his horse; they stood face to face, and both commanded: "Sword out of the sheath".
The swords sprang out in fighting, and so cut above the heads of the two that the whole place was rattling with their blows. Sparks flew so thickly from their fierce slashing that fire covered the ground, and it was impossible to stand long in one place.
Then Doghead said: "Let us not spoil our swords, but put them up and try wrestling".
They laid aside the swords and began to wrestle. Doghead seized Mirko by the body, raised him up in the air, and so planted him on the ground that he sank in it up to the girdle. Mirko, frightened at this, thrust his little finger into the flask, and became so strong that he sprang out of the earth in a moment, rushed at Doghead, and so stretched him on the ground that he lay there like a flattened frog. Then, seizing him by the hair, he dragged him toward the castle, where a golden bridge was built across a bottomless lake. Having brought him to the middle of the bridge, he held his head above the water and commanded the sword to cut. The head fell into the bottomless lake, and Mirko threw the body after.
Doghead's daughter saw all this, and was powerfully angry at Mirko, the king's son. When he came before her she turned her face away and would not come to speech with him. But Mirko explained that he could not have done otherwise, for if he had spared Doghead's life, he would have lost his own; but as he had pledged his faith to the princess, he held to his word, and would marry her. The princess approved this, and they agreed to make ready and set out for Mirko's kingdom. The horses were brought, - Doghead's magic steed for the princess. They mounted the horses, but when ready to start, Mirko became very sorrowful.
"Why art thou sad Mirko?" inquired the princess.
"Because," said he, "I wish greatly to go home, but it is hard to leave this glorious, seven-story diamond castle here, which was thy father's, for there is none like it in our kingdom".
"Oh, my dear," said the princess, "I will turn it at once into a golden apple. I will sit in the middle of the apple; thou mayst put it in thy pocket, and thus carry home the castle and me. There thou canst change it back again whenever the wish comes".
The beautiful princess came down from her horse, gave the reins to Mirko, and taking out a diamond rod walked around the building and struck it on the sides with the rod. The castle began to shrink together, and became smaller and smaller until it was the size of a watchman's booth. Then she jumped in and it became a golden apple, but the diamond rod remained on the ground outside. Mirko, the king's son, picked up the golden apple and the diamond rod, put them in his pocket, sat on his steed, and leading Doghead's horse by the bridle, travelled home comfortably.
When Mirko had come home and seen his horses in the stable he went to the palace, where he found the old king with the Hero of the Plain, satisfied and amused. He told them that he had conquered Dog-head and put him to death; but the old king and the Hero of the Plain shook their heads.
Mirko, taking them both by the hands, said: "Come with me, and I will show you, so that ye may see with your own eyes that I have beaten Doghead; for not only have I brought his seven-story diamond castle with me, but his loveliest daughter with the castle, as proof of my work".
The old king and the Hero of the Plain marvelled at Mirko's speech, and were in doubt; but they went with him, and he led them to the flowery garden of the palace, in the middle of which Mirko took a beautiful spacious place for the diamond castle, where he put down the golden apple. He began to turn and strike it on the sides with the diamond rod. The apple swelled out and began to extend with four corners, and grew greater and greater, till it became a seven-story diamond castle as high as the trees.
Then taking them by the hands he led them up the diamond staircase and entered the halls of the castle, where the world-renowned beautiful princess met and received them with a good heart. Then she sent for the old king's other sons and the chief men of his court. In the dining-hall was a great horse-shoe table. She commanded it; the table opened of itself, and every kind of precious meat and drink appeared upon it. Then the assembled guests feasted joyously. The old king was satisfied at last with his son. He gave Mirko his kingdom and all his possessions, but he withdrew himself to quiet private life, with the Hero of the Plain, and many a pleasant day the old comrades had together; and the old king's two eyes were always laughing. The royal pair lived happily, and had beautiful children. They are still alive if they are not dead.