Plot
Alexander is born a son of Philip II, king of Macedonia and Olympias, a snake witch and priestess. Desiring to attain 'speed', Alexander heads to the woods with allies Philotas and Hephaestion, where he tames a wild man-eating horse, which he names Bucephalus. At the same time he meets and befriends Cleitus and Ptolemy I Soter, recruiting them to join his cavalry. Macedonia heads to war with Athens, led by King Philip and his top advisers, Attalus, Parmenion (father of Philotas) and Antipater. Philip becomes concerned with Alexander's absence, but Alexander and his cavalry arrive at the last moment, exploiting a break in the Athenian lines and leading Macedonia to a victory. After their defeat, Athens ambassadors head to Persia, where they hope to make an alliance with new king Darius III of Persia. Alexander and his friends sneak in as Athens slaves and then kill the guards, causing Darius and his followers to think that Athens is betraying them. Darius quickly executes the Athenian ambassadors, while Alexander wanders into the Hanging Gardens of Babylon and meets a woman named Roxanne. Ptolemy is caught by the Persian army and is suspended in the air, but Alexander saves him from an execution at the last minute by releasing all the horses in the city from their stables, and creating a chaos big enough to escape with his group.
Attalus tricks Philip into thinking that Olympias and Alexander are trying to betray him. Philip banishes Olympias and marries Attalus's daughter Eurydice, who gives birth to a son that Philip plans to make his heir and future king instead of Alexander. Philip holds a great ceremony to present the new prince to the masses and also constructs a huge golden statue of himself, declaring himself a God. During the ceremony the statue crumbles, and a guard hypnotized by Olympias assassinates Philip. It is also implied that shortly after, while successfully driving Eurydice into madness, Olympias herself kills both Eurydice and her baby.
Following Philip's death Alexander ascends to King and Attalus is executed. Athens, led by Demosthenes, plots to fight back against Macedonia, doubting Alexander's strength, but relents once Macedonia defeats the powerful city of Thebes in battle. Alexander places severe demands on Athens but relents on most of them after meeting with the philosopher Diogenes of Sinope and becoming impressed by his wisdom, as well as his simple life and philosophy. Alexander next plots an attack on Persia and starts leading his troops there. Around this time Parmenion reveals to Philotas a secret about Alexander: that prior to his birth Olympias proclaimed that he would destroy the world. In addition, Aristotle, a renowned philosopher and former teacher of Alexander, sends his niece, Cassandra, to join Alexander's cavalry. Macedonia's forces continue to head through Persia's territories with multiple victories. Along the way Alexander recruits the doctor Phillipas to join him after cutting the famous Gordian's Knot (which was said that could only be undone by the King of the World) with his sword. In their next battle with Persia, Macedonia's troops are hopelessly outnumbered by Persia's, which are 10 times that of Macedonia's, but Darius tells his forces to retreat when members of the mysterious Pythagorean Cult intervene. During the battle Philotas falls off his horse and has a vision of Olympias summoning demons.
While in Egypt, Alexander meets Dinocrates, a member of his army who tells him of the great city he wishes to create there: Alexandria. Alexander has a vision of himself being in Alexandria 100 years after his death, where he visits the place where he was entombed by Ptolemy. Before leaving Egypt Alexander and his men visit the Temple of Ammon, where they witness an oracle's prophecy about Alexander being killed by the one person he trusts the most. Ptolemy witnesses a separate prophecy that tells him he will become a "Great King of the World". Plotting with Persia, Pythagorean cult members make another attempt on Alexander's life but he is able to fight them off. Darius leads Persia's armies against Macedonia's. Aristotle meanwhile meets with Diogenes, requesting the Plato-Hedron, a device created by Aristotle's teacher Plato, which contains the knowledge of the entire world. Diogenes claims however that he tossed it aside. The two watch as the battle continues. The Macedonian army gains new strength when there is an eclipse of the moon, and the Plato-Hedron appears and ascends to the heavens. As the battle nears its conclusion, Alexander kills Darius, defeating the Persians once and for all.
With Persia now part of his empire, Alexander recruits Satibarzanes, Darius's former adviser and Satrap, to become a top adviser of his. The Macedonian army becomes concerned that Alexander wants to continue heading east rather than return to Macedonia. Philotas dismisses their complaints but doesn't tell Alexander. Aristotle is also concerned with Alexander's actions and tells Cassandra that she will have to kill him should he continue to push eastward. Phillipas, secretly a member of the Pythagorean cult, plots with them to kill Alexander during his wedding to Roxanne through the use of a dancer possessing poison. During the battle she poisons Alexander but is killed before finishing him off. Satibarzanes frames Parmenion and Philotas for treason. Parmenion is killed by the plotters and Philotas is tied up and stoned to death. When Alexander arrives during the stoning, Philotas requests he let him die so as to not show weakness to the Persians. Phillipas, who treats Alexander, has the opportunity to poison Alexander but instead reveals the truth to him and provides Alexander the means to heal himself, then kills himself with the poison intended for Alexander.
After executing Satibarzanes and the other Persian traitors, Alexander leads his forces towards India. Aristotle provides Cassandra with a parchment that she is instructed to read when they reach India. They reach India where they see a large number of horse-like men known as the Brahman priests. Cleitus, becoming increasingly suspicious of Alexander, questions his motives. At this moment, the Brahman suddenly attack, interrupting them. As Alexander and Cleitus fend them off, Cassandra reads the parchment, putting her under a spell from Aristotle to kill Alexander. When she lunges towards him, Cleitus steps in the way and takes the fatal wound himself.
Alexander and the others continue through India, where they encounter a massive army made up of all the soldiers they have killed over the years. During the battle, Hephaestion is killed when Alexander fights the ghost of Darius. Alexander then rides on into a column of light and faces off against King Porus, who takes on Alexander's appearance. Stating that the world tells him to destroy himself, Alexander defeats his doppelganger in combat. He then encounters Pythagoras at the end of the world, but Pythagoras has no interest in stopping Alexander from destroying the world. He echoes Diogenes' words to Alexander that by destroying the world, Alexander will be creating it anew. Alexander seemingly embraces his destiny as destroyer of the world, but the world does not end: instead, the dark skies clear and Alexander emerges from a pillar of light facing west. He decrees that destiny now points him that way, and embarks for Macedonia.
After Alexander and his army return to Macedonia, Aristotle receives a letter from Cassandra informing him that she has chosen to stay with Alexander of her own will; it is then revealed that Aristotle does not recognize his niece's name and is now amnesiac. Later, a handmaiden attempts to find Alexander to tell him that Roxanne is pregnant. Elsewhere, Alexander is asked to get out of the light by a child drawing geometric shapes and writing formulas on the ground. Motivated by his own prophecy, Ptolemy attempts to stab Alexander, but Alexander prevents him. He then lets Ptolemy escape, stating that Ptolemy's prophecy is unchanged. Alexander turns back to the child's work, and Cassandra asks what he is looking at. Alexander replies that he is witnessing the world he destroyed being reborn.
At this moment, a soldier appears and announces that they are ready to depart for Arabia. As Alexander walks off, it is revealed that the child's name is Euclid, and he pulls out a small version of the Platohedron from his pocket: this implies that the destruction of the world was metaphysical in nature, and that the new world spearheaded by the sciences of Euclidean geometry and Ptolemy I Soter's future breakthroughs has now replaced the old world of Aristotle, Plato and Pythagoras, ushering a new era for all mankind. The final scene depicts Euclid's Platohedron resting on the ground next to his diagrams, catching the sun's dying rays, which transitions into a stark image of a statue and pillar of Alexander, showing him atop his horse and set against the sun and a crimson sky.
