In medieval Russia (or "Finlandia"), the Asiatic barbarians known as the Tugars (and their leader, Khan — no, Colin, no, Kalin) are ravaging and pillaging the land along with their fire-breathing three-headed flying dragonnote . One man pleads to serve the barbarians if they spare him, and promises to be a double agent for them. During all of this, the strong but lame Ilya Muromets sits helpless at his window as his townsfolk are attacked by the cruel invaders. The Tugars also abduct Ilya's beloved, Vasilisa. This important plot point is, of course, completely cut from several localizations of the movie.note
Meanwhile, the aging giant knight Svyatogor (or "Invincor" to dub watchers) gives his sword to some travelers to be passed on to a new bogatyr. Invincor and his horse turn to stone soon after... for reasons that the localization brushes over. The travelers soon come upon a lone house in the country where the previously seen (if you're watching the original) cripple Ilya Muromets resides. His legs haven't worked since childhood, but the travelers miraculously happen to have a magical potion which cures his ailment (in the original, there was also some patriotic singing involved). The travelers give the restored Ilya Invincor's magic sword. Ilya's parents magically show up just in time to see Ilya tear up the lawnnote , though they're happy he can finally do work around the house.
However, Ilya is called off to go and fight the forces of the Tugars. The family wishes him well. Ilya's neighbor gives him a pony named Chestnut Gray. After coating the small horse in Mountain Dewnote for three mornings, Chestnut Gray grows into a massive steed. Ilya passes by through woods and is eventually confronted by a forest-dwelling monster known as Nightingale the Robber, or just "Wind Demon", who blows wind so hard it parts the forest backward. Of course, Ilya defeats him by throwing a cudgel at the branch the Wind Demon is sitting on, knocking the demon senseless. Ilya travels to the capital of Kiev and presents the forest monster to the king, who is impressed with his deeds. Ilya becomes part of a bogatyr brotherhood with two other knights, one of whom happens to be known for being Sinbad.note
The Tugars send an envoy to the city, a massive fat man on an impossibly larger moving platform, who warns the king to give them a tribute for 12 years in advance and they will be spared from Kalin's wrath. Ilya replies by throwing insults at the human blimp. The blimp throws a sword back, which is, naturally, delivered back by Ilya in a rather lethal manner. Much of the envoy is smashed by Ilya using the corpse as a club, the rest run off. While people completely forget about the implied threat that Kalin's men will one day return, Ilya rediscovers his wife Velia, who had been kidnapped by the Tugars in one of the many scenes removed from the American version. In fact, the dub makes Ilya look disturbingly creepy toward this woman he's apparently never met, despite nearly making out with her the whole time and swearing he'll never leave her alone again.
Unfortunately the wife is quickly abducted by the Tugars. Again. Hands up, those of you who didn't see this coming? This time, though, Velia bears Ilya a young son, who is taken to be trained as a Tugar warrior. His name is Little Falcon, as that is what saw them conceive the child.
The double-agent from long, long ago tricks the king and Ilya is imprisoned for many years in the castle's dungeons while the Tugars continue to destroy the countryside. They set up camp outside the city of Kiev, ordering seven hundred carts of gold to be given to the Tugar leader Kalin in order for the city to be spared. Eventually the double-agent is rooted out and thrown into boiling pitch, while Ilya is finally released and allowed to lead the amassed armies of the land against the Tugar hordes. Kalin starts to move more of his Tugar hordes toward the city of Kiev. Ilya hatches a plan to trick the Kalin by using torn sacks and broken carts to create the impression that all of the gold being paid as tribute fell out during transport. The supposed search for the gold takes a day. Then, the Tugars are forced to give Kalin a mountain of the gold they, apparently, wanted to keep for themselves (in reality, it was their own jewelry — Ilya's plan at work). This takes about one day more. Then, Kalin demands Ilya Muromets, and the supposed search for him takes two more days. Ilya gets Kalin frustrated enough to claim that he'd cancel the invasion if the hero would stand before him; Ilya promptly reveals himself to the Kalin — who feels insulted by this deception and decides to attack anyway; Ilya escapes and goes to prepare his army.
What this quite has to do with getting Kalin to not attack and leave, however, is anyone's guess (except for the fact that he tricked Kalin into promising to leave, but since when do villains care). However, the reserves did arrive in the meantime...
Ilya's son Little Falcon is now grown up and a strong Tugar warrior and is sent to fight Ilya. While they duel, Ilya sees the ring he once gave to his wife on Little Falcon's finger. Quickly, Ilya reveals the boy's true heritage to him. Amazingly, Little Falcon quickly defects from all he knew and joins the side of a guy who randomly claimed to be his fa... wait, mythology and family values, let's rephrase that: Naturally, he joins his father's side (largely due to suddenly seeing his mother's face in the ring), goes to rescue his mom, and still makes it back in time to join the dragonslaying..
The two other knights in Ilya's brotherhood each lead one army with Ilya leading a center army toward the Tugar hordes. Kalin orders a massive pyramid to be made out of human bodies so... um... so he can be atop it (well, view the battlefield, actually, though it is unclear whether the number of his warriors who suffocated inside was worth the tactical advantage). A ballista arrow hits the pile, making him roll down. Angrily, Kalin orders to release the three-headed dragon named Zmey Gorynych (in Corman's translation it's Zuma the Dragon,note ) to burn Kiev into ashes. However, another ballista arrow hits Gorynych in the wing, forcing it to fight on the ground. More of the Russian (or not) soldiers land from ships from a nearby river and fight the dragon, eventually slaying it. The Tugar hordes are routed and Kalin is captured. The victorious Ilya is offered to become a noble by the current king but declines in order to be with his wife and go on other journeys. Ilya instead gives his son the sword of "Invincor" and declares that Falcon will receive said rewards and continue the heroic lineage.