In northern
Britannia, AD 62, Roman soldiers led by General Quintus Attius Corvus wipe out a tribe of
Celtic horsemen. Corvus personally kills the parents of a boy named Milo. Being the only survivor, Milo is later captured by slave traders. Seventeen years later, in
Londinium in AD 79, the grown Milo becomes a popular
gladiator. His owner Graecus brings the gladiators to Pompeii. Also going there are Cassia and her servant Ariadne, who return after a year in
Rome. Cassia becomes enamored of Milo after witnessing him perform a
mercy kill of a critically injured
horse; she reveres this as an act of kindness. Her parents are the city governor Severus and his wife Aurelia. One of their servants is later swallowed up when a quake from
Mount Vesuvius opens up the ground under him. In Pompeii, Milo develops a rivalry with Atticus, a champion gladiator who, by Roman law, will be given his freedom after he earns one more victory. The gladiators are shown off at a party where Corvus, now a Senator, announces that he will invest in Severus' plans to rebuild Pompeii. It is then revealed that Cassia originally left Rome to escape Corvus' unreciprocal advances. When an earthquake causes some horses to become anxious, Milo is permitted to calm one down. He then takes Cassia on a ride. Being aware that they cannot be together, he returns her to the villa. Not recognizing Milo, Corvus is ready to kill him, but Cassia pleads for his life. Milo is lashed for his actions, and Atticus admits respect for his rival. In the
Amphitheatre of Pompeii, to punish Milo, Corvus orders him killed in the first battle, and trainer Bellator convinces Graecus to execute Atticus as well. The two men, and other slaves, are chained to rocks as, in an attempt to recreate Corvus' victory over the Celts, gladiators are unleashed upon the slaves. Working together, Milo and Atticus survive the battle, with the latter realizing the Romans will never honor his freedom. Meanwhile, Corvus forces Cassia to agree to marry him by threatening to have her family killed for supposed treason against
Emperor Titus. When Milo and Atticus win, Cassia defies Corvus by holding a "thumbs-up", saving them from execution. Corvus has her locked up in the villa and has his officer Proculus fight Milo one-on-one. Their battle is interrupted when
Mount Vesuvius erupts, creating tremors that cause the arena to collapse, sending Milo and Proculus crashing to the dungeons. Milo opens up the gates, allowing his fellow gladiators a chance to attack; Proculus escapes, while Bellator is killed. Enraged, the critically injured Severus tries to kill an unconscious Corvus, only for him to awaken, stab him instead and escape. Flaming debris rains down upon the city as everyone tries to flee to the harbor. One fireball sinks a ship, killing the escaping Graecus. Before succumbing to her injuries, Aurelia tells Milo that Cassia is at the villa. There, Milo manages to save Cassia, but Ariadne is killed when the villa collapses into the
Mediterranean Sea. Atticus tries to reach the harbor, which is destroyed with several ships when a
tsunami created by the volcano smashes into the city. Reuniting with Atticus, Milo suggests searching the arena for horses to escape. As the gladiators face Roman soldiers at the arena, Cassia is abducted by Corvus. Milo chases after the chariot carrying the two while Atticus fights Proculus. Atticus is mortally wounded in the duel, but nonetheless manages to kill Proculus. Cassia frees herself before the chariot crashes into the
Temple of Apollo. Milo and Corvus duel aboard the chariot as a
fireball destroys the temple. Cassia then chains Corvus to a building, as Milo reveals who he is. He declares that
his gods are coming to punish Corvus. Milo and Cassia ride off as a
pyroclastic surge races into the city, incinerating Corvus. At the arena, Atticus proclaims that he dies a free man before being consumed with the city. At the outskirts, the horse throws off Milo and Cassia. Milo tells Cassia to leave him, explaining the horse is not fast enough to carry them both. Instead, she sends the horse off, knowing they cannot outrun the surge. In their final moments, they kiss as the surge engulfs them. When the dust settles, their petrified bodies are shown in an eternal embrace. ==Cast==