Immortal tyrant Kortan raids a village for slaves. Young Quentin MacLeod and his mother are killed in the attack but Quentin soon revives. Immortals Ramirez and Mangus help him and his kid stepsister Clyde find their captured clansmen.

Ramirez takes Quentin and Clyde to his old friend Stevenson, a brilliant Immortal scientist who lives in a defunct hydroelectric power plant turned library and possesses the knowledge of electricity. But something doesn't feel right.

Quentin's Dundee clan is attacked and robbed by a gang of raiders led by Mohar, an evil thug who has found a working machine gun. Quentin steals the gun to retrieve his clan's stolen supplies but becomes tempted by its deadly power.

Ramirez takes Quentin and Clyde to an old mining complex to meet his Immortal friend Erol, an expert in explosives, oil and mining. However, they only find Erol's traumatized, delusional and unhinged mortal assistant Melvyn there, who has, in his madness, convinced himself that he too is one of the Immortals. He abuses their trust to trap them in the mine, kidnaps Clyde thinking she's his dead daughter and takes her with him to Mogonda on a suicide mission of revenge to kill Kortan with Erol's explosives.

During a severe thunderstorm, Ramirez, Quentin and Clyde are forced by Kortan's pursuing forces to hide in the Iron City, a gigantic abandoned aircraft carrier shipwreck that lies in the middle of a desert. Kortan himself arrives to fight Quentin one on one. During their battle, Quentin is temporarily blinded by lighting but fights on. Also, Ramirez reveals to Quentin Connor MacLeod's martyrish ultimate fate.

The trio is in a cliffside village to find Immortal Olak who possesses the knowledge of wind and flying and is willing to transfer it to Quentin through the "quickening of knowledge" ritual, if he can save the chieftain's son from Arak.

Ramirez, Quentin and Clyde stumble upon a small matriarchal seaside community connected to the shore only by a single suspension bridge, which protects them from Kortan's forces. The townswomen have lost many of their husbands and sons in Arak's slave raids, so they've come up with a plan to leave the country and Kortan's grasp for good. They still posses the lost knowledge of shipbuilding, so they"ve constructed in secrecy a huge sailboat. However, Arak arrives and promises to release their men from slavery if the women turn over the fugitive trio.

Ramirez is taking Quentin to meet Lanceley, an Immortal who possesses the knowledge of history. To stop him, Kortan sends Arak and his forces to Lanceley's rundown citadel where he and his feisty followers live.

Quentin must reach Immortal Ilrick and receive from him the knowledge of medicine to cure both his and a xenophobic rival clan from malaria. Meanwhile, evil scientist Asklepios is promoted and Arak demoted by Kortan.

Ramirez takes Quentin to see Immortal Sahevy who possesses the knowledge of botany and agriculture. However, the forest he lives in has been taken over by man-eating plants. The locals blame Sahevy and even accuse him of treachery.

Ramirez takes Quentin to see the Sandman, a tormented Immortal once known as Prometheus, who possesses the forbidden knowledge of atom and nuclear weapons. Kortan tries to get to him first and kill him to absorb this knowledge.

The trio travels to see Brana, the Immortal who possesses the knowledge of linguistics and Earth's languages. Unfortunately, Arak raids Brana's village and takes the woman he loves for himself. Brana asks the trio for help.