Set in the near future, Allochthon follows a group who are in possession of a rejuvenation treatment that promises greatly increased longevity. Bruce is a member of the team that samples extremophile microbes to support this development work and is well aware of its potential to destabilise an overpopulated planet already suffering from the impacts of global warming. Despite its huge potential value to their pharmaceutical sponsors, his boss decides to keep their findings under wraps until they can find a way to ensure that it does more good than harm.

However, a cabal of aging plutocrats, led by a competing mega-corporation, have a continuous programme of industrial espionage aimed to take complete control of this resource. Bruce hopes to divert attention from the research group but, during a sampling trip, the cabal launch pre-emptive attacks to remove their competition, completely regardless of collateral damage on a huge scale.

By luck alone, Bruce and his partner Marion survive the initial attacks and learn that his boss is also alive even though Marion's girlfriend - his boss's daughter - is dead. They are now on a mission to eliminate those responsible and revenge fallen colleagues, despite still being in the cross-hairs of their opponents.