In prehistoric times, a young Cimmerian peasant boy, Conan, learns from his blacksmith father the significance of their god, Crom, and the reliability of steel. Soon after, Vanir raiders led by warlord Thulsa Doom ransack the peasant village, and Conan's parents are killed, the family sword is stolen and Conan is enslaved. After years of hard work turning a mill wheel, the strong Conan is selected to be a gladiator. His success brings him education as a sword master as well as in the written word. Upon unexpectedly receiving his freedom from his long time captor, Conan runs away and stumbles upon Crom’s crypt where he discovers his family sword. Soon after, Conan is invited into a hut by a woman who demands sex in exchange for a prophecy. Conan complies and the woman reveals that Conan will one day become king. The woman also admits that she is a witch and when she attempts to murder Conan, he pushes her into the fire where her spirit escapes in the smoke. The next day, Conan finds Subotai, an archer and thief from Hyrkania, chained outside the hut and frees him. The men become friends and travel to a large village at the center of which is a large temple dedicated to the snake god, Set, whose followers form a religious sect filled with deceivers and murderers. Drunkenly deciding to rob the temple of its valuables, Conan and Subotai encounter Valeria, a reckless fellow thief also intent on breaking into the temple. Conan discovers a large glittering red jewel, but in order to reach it must kill an enormous serpent guardian. After the thieves escape from the temple with various priceless jewels, Conan seduces Valeria. Reveling in their newfound wealth, Conan, Valeria and Subotai fall prey to excessive drunkenness and are easily taken by soldiers of King Osric, who promises the thieves great fortune if they can bring down Thulsa Doom, who has enslaved the king's daughter. Valeria urges Conan to avoid Doom, who resides in a "mountain of power" with a thousand loyal followers, but Conan cannot forget Thulsa's crimes and sets out after him on his own. After days of traveling, Conan comes upon a solitary wizard who befriends him and tells him of Doom’s presence nearby. Conan arrives at the outskirts of Doom's fortress and masquerades as a religious follower to lead a priest away from the group. Knocking out the priest, Conan dons the priest's costume and attempts to blend in with an audience of cultists at one of Doom's speeches. Conan’s unusual stature is quickly noticed, however, and he is taken, tortured and then brought before the cult leader. Doom chides Conan for his actions against his religious followers and Conan accuses him of murdering his father. Unmoved, Doom tells Conan his own personal philosophy that while steel is strong, flesh is stronger and illustrates this principle by beckoning to a follower on the cliffs who readily jumps to her death to be near him. At Doom’s order, Conan is left tied to the “Tree of Woe” in the desert and is near death before being rescued by Subotai and Valeria, who take him to the wizard for treatment. That night, Subotai, Valeria, and the wizard join together to fend off the spirits of death and save Conan's life. After Valeria pledges her devotion to Conan, the friends plot to steal King Osric's daughter from Doom's mountain fortress. After preparing themselves, Conan, Valeria and Subotai sneak into Doom's harem and stage an attack during a service in which Doom turns into an enormous serpent. As Conan and Subatai kill many of Doom's men, Valeria battles her way to the princess and unchains her. As the group escapes, Doom, now returned to human form, fires a snake-arrow at the fleeing party, mortally wounding Valeria. Before dying, she claims her death is the repayment to the gods for Conan's life. Conan and Subotai decide that, instead of running, they will set an ambush for their pursuers with help from the wizard. Before the battle that ensues, Conan prays to his god Crom for revenge. Doom's men fall to the thieves' weapons and carefully laid traps, and Conan defeats Doom's high priest with help from the specter of Valeria. Doom retreats after attempting to silence the princess with a snake arrow, which Subotai deflects. That night, Conan confronts Thulsa Doom during a ceremony at his temple. Doom asserts that, since he shaped Conan's life to such a great degree, he is Conan's true father. Conan rejects the assertion and beheads the warlord with the family sword. Victorious, Conan holds Doom's head aloft to the crowd, which upon realizing Doom's mortality, quickly disperses. Conan hurls away his sword, sets Doom's temple afire and begins the return journey to bring the princess back to King Osric. Over time the prophecy is fulfilled when Conan becomes king.