Set in 2030, the plot of Tiberian Sun is a follow-up to the original game Command & Conquer, after the end of which the Nod leader Kane is presumed dead. In Tiberian Sun, Kane resurfaces from his hideout with improved military forces and new Tiberium-enhanced technologies, determined to convert Earth into a Tiberium world. The GDI commander Michael McNeil is tasked with preventing the world from falling into the hands of Nod, this time with the very means of the extraterrestrial Tiberium substance. Meanwhile, Nod general Anton Slavik must unite a splintered Brotherhood of Nod before joining Kane's fight against GDI. A third faction, Tiberium mutants, are caught in the middle of this fight and join either side, sometimes as playable and sometimes as non-playable characters.
Firestorm follows the events as they unfolded in the GDI campaign of Tiberian Sun. With Nod fractured into feuding warlords following Kane's death, Anton Slavik is determined to keep Kane's ideology alive through the resurrection of Nod's highly advanced artificial intelligence, CABAL (Computer Assisted Biologically Augmented Lifeform). The Global Defense Initiative continues its ongoing campaign to stop the spread of Tiberium and its monstrous mutations by retrieving the extraterrestrial Tacitus device, and decides to take control of CABAL to help it decode the device. In both campaigns, CABAL goes rogue and attempts to conquer the world through the systematic assimilation of human populations into cyborg armies, forcing Nod and GDI to unite temporarily against it. In the Nod ending, the defeated CABAL appears to merge with a resurrected Kane.