Immortals

When the world was young, the gods did battle in the sky. The victors ruled on Mt. Olympus and imprisoned the vanquished -- the Titans -- beneath Mt. Tartarus on Earth. Also lost during the battle is the Bow of Epirus, a mighty weapon that can shoot invincible energy arrows.Centuries later, King Hyperion (Mickey Rourke) mounts a campaign to recover the Bow of Epirus and free the Titans. Bitter over the deaths of his wife and children due to disease, he is resolved to destroy the gods who refused his prayers to spare his family. He overtakes the Sybelline Monastery, imprisoning the virgin oracle Phaedra (Freida Pinto) and her attendants, then lays waste to villages in the area. In one village works the stone mason Theseus (Henry Cavil). Theseus has been trained in the military arts by a mysterious Old Man (John Hurt) who encourages him to be a protector of all humanity; Theseus, whose devout mother was raped and thus considered an outcast, refuses. When the goddess Athena (Isabel Lucas) visits the Old Man, he is revealed to be Zeus (Luke Evans) in human disguise.When Hyperion's forces destroy Theseus's village, he kills Theseus's mother in front of him and imprisons Theseus, where Phaedra and her attendants are also kept. Phaedra inadvertently touches Theseus and has a vision of him as either the savior of humanity or the ally of Hyperion in the destruction of the world. That night, she and her attendants seduce and kill the guards; Phaedra escapes with Theseus and two other slaves, Stavros (Steven Dorff) and Daerios (Alan Van Spring).Although Zeus has forbidden the gods to intervene unless the Titans are freed, Athena, Poseidon (Kellan Lutz) and Ares (Daniel Sharman) determine to protect Theseus as best they can. Phaedra tells Theseus he must return to his village and properly bury his mother. There, Theseus discovers the Bow of Epirus. Hyperion has sent the Minotaur (Robert Maillet) and soldiers to intercept them. The soldiers kill Daerios but, after a brutal battle with the Minotaur, Theseus uses the Bow to free the others. That night, Phaedra makes love to Theseus to free herself from her premonitory powers.The humans make their way to the Sybelline Monastery, where Hyperion has laid another trap. A jackal steals the Bow of Epirus and takes it to Hyperion, but the timely arrival of Athena and Ares saves Thesus, Phaedra and Stavros. This enrages Zeus who kills Ares in punishment but allows Athena to provide horses to Theseus so he can join a last stand against Hyperion's forces.As Theseus leads the fight against Hyperions' army, Hyperion uses the Bow to free the Titans from their prison. This prompts Zeus to intervene, and he, Athena, Poseidon, Heracles and Apollo fight a ferocious battle against the Titans. Theseus confronts Hyperion and, though mortally wounded, finally kills him. The Titans kill all of the gods except Zeus who destroys Mt. Tartarus to contain them again. Zeus takes Athena and Theseus to Olympus with him.Several years later, Phaedra lives in Theseus's village with her son, the result of her coupling with Theseus. The Old Man approaches the boy and tells him to prepare for a coming war in heaven. The boy closes his eyes and has a vision of Theseus leading the gods in battle against the resurgent Titans.---
The following is not a plot synopsis, as Tarsem Singh, regardless of his "vision," is not part of the plot of the film.Visionary director Tarsem Singh (The Cell, The Fall) transports us in this epic tale of treachery, vengeance and destiny in Immortals, a stylish and visually spectacular 3D action adventure. As a power-hungry king razes ancient Greece in search of a legendary weapon, a heroic young villager rises up against him in a thrilling quest as timeless as it is powerful.The brutal and bloodthirsty King Hyperion (Mickey Rourke) and his murderous Heraklion army rampage across Greece in search of the long lost Bow of Epirus. With the invincible Bow, the king will be able to overthrow the Gods of Olympus and become the undisputed master of his world. With ruthless efficiency, Hyperion and his legions destroy everything in their wake, and it seems nothing will stop the evil king's mission.As village after village is obliterated, a stonemason named Theseus (Henry Cavill) vows to avenge his mother, who was killed in one of Hyperion's brutal raids. When Theseus meets the Sybelline Oracle, Phaedra (Freida Pinto), her disturbing visions of the young man's future convince her he is the key to stopping the destruction. With her help, Theseus assembles a small band of followers and embraces his destiny in a final, desperate battle for the future of humanity. Immortals is produced by Gianni Nunnari (300), Mark Canton (300) and Ryan Kavanaugh (The Fighter).

Question: What relative does Theseus vow to avenge?
Answer: mother