Haunted by a recurring nightmare in which he fights Kortan, Quentin decides to go to Mogonda alone and deal with Kortan once and for all. However, he finds allies among Mogonda's shanty town people and they try to steal Kortan's sword.
Kortan locates guilt-ridden satellite expert Sheperd, the Immortal whose miscalculation led to Earth's failure to stop an incoming meteor, which initiated the apocalypse. Sheperd goes on the run to find Quentin and give him his knowledge.
Ramirez takes unruly Quentin to the ruins of a city that was destroyed in the apocalypse to see how most teenagers live now. They witness a street fight between two teenage gangs and Quentin decides to try to make peace between them.
While raiding "451opolis", a concealed town founded by a deserter from one of his slave hunter squads, Arak finds a huge library. Since Kortan has banned all books, he plans to burn it down. Can Ramirez stop him?
The trio visits Orane, a friendly blue-haired female Immortal who runs a technologically advanced underwater city and possesses the knowledge of oceanography and marine life. However, Kortan and his forces manage to track them down.
Kortan traps the trio in his escape-proof unisex prison where inmates are brainwashed to worship him and join Kortan's army of hunters. The trio tries to liberate them both physically and mentally. Arak's backstory is revealed.
After a skirmish, Ramirez suddenly begins insisting that Quentin is ready to duel Kortan. Clyde is suspicious of this sudden change of heart, especially after Ramirez, uncharacteristically annoyed by her complaining, smacks her.
Ramirez takes Quentin to see Cornell, an Immortal with the knowledge of astronomy, acuity and directions. However, Cornell plans to use this knowledge to defeat Kortan during the upcoming solar eclipse and won't give it up.
The trio runs into the Hurricane People, a mystical cult of Immortals who live in seclusion. They know a secret method of extracting electric power from whirlwinds, so Ramirez tries to convince them to share this knowledge with Quentin.
Arak captures Dundee chieftain Niel. Kortan decides to erase his memory and replace Malone with him as the new court jester and living key to Kortan's armory. To keep his job, Malone offers to help the trio free Niel. Can they trust him?
Kortan leaves Asklepios in charge for a day. Meanwhile, the trio must infiltrate Kortan's nuclear power plant that provides Mogonda with electricity to rescue Volta, the Immortal who possesses the knowledge of nuclear energy.
Arak's forces have the Dundees cornered. Ramirez helps them organize defenses which buys the clan some time. The trio and a couple of clansmen then leave for Mogonda to create a diversion even Kortan and Arak can't ignore.
Asklepios is mortally hurt during Arak's skirmish against the trio. Asklepios' protegee Valka, the head of Kortan's spy network, is devastated. Malone suggests that the blood of an Immortal can heal him.
Fearing that she, her mentor Asklepios and their class of bureaucrats will lose their positions to Arak and his hunters, Valka contacts the trio, gives them files her spies have on rebel groups and asks them to kill Arak in return.
NASA's space shuttle returns to Earth after 700 years and crash-lands. Kortan's sleazy Immortal friend Emerson who knows the secret to invisibility is the only survivor. Kortan gets to him before the trio.
With Arak and his hunters in pursuit, the trio hides in the ruins of a subway. However, one train still works and takes them to Zack, a friendly hermit who can talk to dangerous giant ants called Anomas. Arak locates them.
On the run from Arak's forces, the trio finds a young boy named Doogie, who lives in an old tower. Ramirez notices Leonardo da Vinci's invention there. Doogie asks them to wait for his grandfather, but Kortan and Arak show up instead.
The trio is captured by a tribe of wild Grans, the ape-dog hybrids that Clyde's pet Gaul belongs to. The tribe's eccentric human pet O'Kief informs them that Gaul must fight the tribe's champion for their freedom. Arak attacks as well.
General Kirk sends Kortan's conditioned Anomas against the rebels in Mogonda's shantytown. In retaliation, the rebels bring wild Anomas into town. Immortal Mahata gives his knowledge of entomology to Quentin, who tries to end the carnage.
Immortal Eva, who possesses the knowledge of holography, refuses to aid Kortan and escapes his clutches. The trio finds her and she transfers her knowledge to Quentin, but Arak kidnaps Clyde and takes her to Kortan's holographic facility.
The trio must help Immortal Fredrickson, a brilliant scientist who possesses the knowledge of genetics and is working on ways to revive extinct species, to defeat his evil clone who wants The Prize for himself.
The trio arrives in a mining town ruled by a death cult that demands human sacrifices to appease the Immortal god Quentin MacLeod. Quentin suspects this is Kortan's doing but can he prove it to the angry villagers who want to lynch him.
Asklepios has created a giant laser super weapon that can torch a whole region in a second. The trio creates a diversion by pitting jealous Arak against Asklepios and tries to reach the weapon and use it on Mogonda.
While on the run from Arak's forces, a bad fall gives Ramirez amnesia. He now remembers nothing about his oath or Quentin and goes to fight Kortan himself. Kortan tries to kill two birds with one stone by pitting Ramirez against Quentin.
Pursued by Arak's forces, the trio enters an icy region and stumbles upon a friendly Inuit tribe of the Igalaks led by wise Takanuk, who live in such total seclusion that they don't even know about the apocalypse or Kortan. Arak locates them, so Ramirez uses an ancient submarine that the Inuits have found in the ice to try to stop him.
Asklepios makes an ancient missile launch control center operational again, so Kortan gives Quentin's clan an ultimatum - either they deliver Quentin to him within 12 hours or they will be annihilated. The series ends on an open ending.