During the Hyborean age, a period known for its high adventure, a blacksmith named Nial (William Smith) forges a masterful sword. Once completed, he shows it to his young son, Conan (Jorge Sanz), imparting wisdom about their god, Crom, who resides within the Earth, along with the importance of "the Riddle of Steel" that every warrior must decipher to gain entry into Valhalla. Nial warns Conan not to place his trust in men, women, or beasts but assures him, "But this you can trust," while gesturing toward the sword he has crafted.
As winter descends upon Conan's village, located in the forest and inhabited by the Cimmerians, dark and mysterious black riders, adorned with a serpent emblem, ruthlessly attack the village. Despite the villagers' brave resistance, they are no match for the skilled assailants. Nial valiantly slaughters several of their attackers but ultimately succumbs to the onslaught, falling prey to their dogs.
In the aftermath of the brutal raid, Conan's mother Maeve (Nadiuska) stands as the last line of defense, clutching her sword while safeguarding her son. As they face the leader of the marauders, Thulsa Doom (James Earl Jones), a chilling figure with hypnotic blue eyes, Maeve holds her ground. However, she falls under Doom's mesmerizing gaze and tragically loses her life at his hand, leaving young Conan in despair. As the village burns around them, Conan and the remaining children are taken captive as slaves.
Sold to a tribe known as the Vanir, Conan and the other children labor at a massive grain mill called the Wheel of Pain. As time goes by, young Conan matures into adulthood, portrayed by Arnold Schwarzenegger, growing immensely muscular during his grueling servitude. Eventually, he is purchased by a fierce, red-haired warrior who trains him as a pit fighter. Although initially perplexed by the violence, Conan quickly masters various combat techniques and becomes a champion, earning riches for his owner.
After some time, his master, inebriated, decides to free him. Newly liberated, Conan finds himself pursued by wolves across the rugged landscape. Seeking refuge, he climbs a rocky cairn and stumbles upon the tomb of an Atlantean general, reclaiming his ancient sword and equipment for self-defense. Utilizing the sword, he breaks free of his chains, wearing a victorious smirk as the wolves close in.
Equipped with newfound weapons, Conan embarks on a journey and meets a beautiful woman who possesses some mystical insight. Intrigued, he inquires about a serpent symbol he seeks, only to find himself entangled in an unsettling incident when she transforms into a demon, forcing him to cast her into the flames.
In the following morning light, Conan encounters Subotai (Gerry Lopez), a Hykanian thief, and the two join forces, venturing through towns in search of information about the serpent symbol. They learn of a powerful snake cult, prompting them to raid its temple for rumored treasures, including the coveted "Eye of the Serpent."
Assisted by Valeria (Sandahl Bergman), another skilled thief they meet during their escapades, they descend into perilous depths, only to awaken a formidable serpent while attempting to steal from the pit. Navigating through ceremony and chaos, they narrowly escape with their lives.
Their misadventures lead them to confront the King, who unexpectedly praises them for defying the cult and enlists their help to rescue his daughter, Princess Yasimina (Valérie Quennessen), ensnared by the sinister Thulsa Doom. As Valeria expresses concern for their future, Conan departs alone on his quest, driven not only to save the princess but also to avenge the tragic loss of his family and his people.
After confronting supernatural challenges and assembling allies like Akiro (Mako), an old wizard, Conan ventures into the heart of Doom's lair. Disguised within the cult, he faces the dark leader himself, who not only recalls the misdeeds he has committed but also tries to ensnare Conan in a trance.
Left for dead, Conan is ultimately rescued by his devoted friends, who help heal him and prepare for the next battle. Tension mounts as they infiltrate Doom's stronghold, igniting chaos among the cult’s followers. Despite the overwhelming odds, Conan, Valeria, and Subotai mount a daring escape with the princess, only to face Doom's wrath once more.
In the climactic showdown, Valeria is mortally wounded, prompting a fierce battle between Conan and Doom’s henchmen before the final confrontation with Doom himself. Ultimately, Conan breaks free from the curse of Doom’s hypnotic influence and slays the dark antagonist, liberating the cult’s followers from his grasp.
In the final moments, Conan contemplates his next moves, burning Doom's temple in a defiant act. Returning Yasimina to her father, he prepares for whatever adventures lie ahead, hinting at a future where Conan will one day claim a throne of his own creation.
