Ivan finally possesses the strength of a true hero after defeating the evil sorcerer Rogoleb. Now, as the land of Belogorye prepares for a grand celebration, Ivan and Vasilisa are set to marry. They are in the midst of resolving the classic challenges faced by any new couple. Meanwhile, Kashchei forges wedding rings and Svetozar enlarges butterflies to be released instead of the pigeons that were regrettably eaten by the ever-hungry Kolobok. Additionally, Baba Yaga has conjured magical wings for her hut, inviting the newlyweds to embark on a honeymoon adventure.
However, just as the festivities are set to begin, misfortune strikes when Vasilisa is kidnapped. As Ivan and his companions give chase, they unexpectedly find themselves transported to modern-day Moscow, facing the challenges of adapting to an unfamiliar world. During the frantic pursuit for Galina, a mysterious black knight, sent by her, crashes into Baba Yaga's hut. This incident causes Koschei to separate from the group, resulting in his head being thrown into a passing car while his body lands on the deck of a ship sailing the Moscow River, where Kolobok happens to be.
Caught on the ship, Koschei and Kolobok must join forces to find Koschei’s head and reunite with Ivan, who is despondent over Vasilisa’s abduction. In order to pick up Vasilisa’s trail, they seek outside assistance, as Galina is well-hidden. They discover a firebird feather, which may guide Ivan toward her. Despite Koschei having long ago exterminated the firebirds in Belogorye, some have survived and fled to Moscow to escape the impending darkness. Svetozar magically sends Ivan's phone to Koschei, turning the device into a bird; however, Kolobok accidentally swallows it, leaving Ivan unable to connect.
Baba Yaga, Svetozar, and Vodyanoy, adopting a guise to avoid suspicion, arrive in the high-rise district of Moscow, experiencing a taxi ride for the very first time, much to the surprise of the terrified taxi driver. Upon entering the so-called “firebird’s nest,” Ivan unexpectedly encounters pop star Philip Kirkorov, who dismisses the plight of Belogorye’s inhabitants as irrelevant. During the encounter, the firebird lays a magic egg that can answer any question, but things take a turn when Ivan decides to steal the egg while the birds are distracted. The mermaid also expresses interest in the magic grain that can transform them into humans during performances.
Meanwhile, a woman inadvertently takes Koschei’s head in a grocery bag home, where her son mistakes it for a plaything. Koschei's body, alongside Kolobok, is not idle either; they manage to procure a bicycle to speed up their search for Ivan. They eventually learn of the head’s location, thanks to an apartment’s owner who finds it unusual but decides against tossing it out. Unbeknownst to them, the heroes of the fairy tale struggle to contact Ivan.
At the same time, Vasilisa is stuck in captivity, believing she will eventually be rescued. However, Galina reveals a shocking truth: the villain Ivan thinks he is up against is actually his mother, who only seeks to reunite with him. After receiving a drop of blood from Vasilisa, Galina transforms into her, intending to deceive Ivan and his friends.
The magic egg proves problematic, refusing to open, chiding, “Open tomorrow,” regardless of Ivan's efforts. When time passes, the egg remains resolute; even Yaga’s aging potion fails to influence its stubbornness. After a night of anguish and driving aimlessly around the city, Ivan is abruptly confronted by the knight who kidnapped Vasilisa, leading to an intense confrontation. Surviving only by chance, Ivan’s fate becomes more perilous.
In a twist of fate, Vodyanoy proposes a method to find a kikimore, a creature that feastes on human time. These beings had once been evicted from Belogorye but found ways to continue their unsavory habits. The kikimoras have created a “time stone,” a powerful crystal that can manipulate time. Ivan and his allies find themselves in the post office where the kikimors are disguised as postal workers. Frustrated by their demeanor, Ivan unleashes his anger, demolishing the surroundings. The kikimora, frightened by Ivan’s show of strength, leads him to the crystal.
As time ticks by, disaster looms as Galina, disguised as Vasilisa, tricks Svetozar into taking her home. The group encounters the firebirds, furious over their stolen egg, just as Koschei arrives to aid his friends by creating a portal to “tomorrow,” enabling Ivan to interact with the egg.
Through the portal, the egg guides Ivan on his quest to find Vasilisa. Confronted by numerous obstacles, Ivan learns that Galina has closed off his bride. The climax escalates dramatically when Galina kills Vasilisa, inciting Ivan's rage. In his anguish, he mistakenly kills Svetozar, not realizing Galina had taken his form. Blinded by hatred, Ivan raises his weapon against Galina. She takes this moment to reveal a painful truth: she is indeed his mother and has manipulated events to awaken the darkness residing in him through years of separation.
Galina’s sinister plan involved stealing Vasilisa and inciting Ivan to succumb to his darker self. Despite the darkness threatening to consume him, Ivan is determined to resist. Just as hope seems lost, Koschei sacrifices himself, encouraging Ivan to create a time portal to prevent the darkness from manifesting in the past.
Time shifts back; Ivan encounters Mikula, the future Koschei, on the brink of darkness. A swift dialogue leads to an unexpected confrontation with the Messenger of Darkness, who reveals itself as Ivan's dark side. Choosing to control his thoughts over facing the darkness, Ivan finds solace. Recognizing that the Messenger is part of him, he confronts it differently by embracing and mastering his emotions. Finally defeating the Messenger, Ivan ensures that darkness cannot overshadow his future.
In the end, Ivan sacrifices his weapon in the Black Lake, expelling darkness forever. In Belogorye, the tale concludes with heroes living harmoniously. Ilya Muromets, Dobrynya Nikitich, and Alyosha Popovich cherish their friendship, while Vasilisa and Ivan, now free from darkness, lead a blissful life together, observing the beautiful future for their children.
