Red Dwarf is stolen from the crew and they are forced to survive on Starbug. They go into deep sleep and are revived 200 years later when there is a chance to recapture the ship.
In order to gain more ground on Red Dwarf they try to go through an asteroid belt but find that it is inhabited by alien beings called Psirens who use mind control to lure their victims and then suck out their brains.
The gang is attacked by a simulant ship who upgrade Starbug with laser cannons and defensive shields and then force them to play a game of 'cat and mouse'. The crew decide not to flee but to stay and fight ,which surprises the simulants. Before their ship is crippled by Starbugs new offensive weapons, the simulants upload a killer virus into Starbug's navicomp. Kryten then transfers the virus to his CPU in an attempt to eradicate it. The gang watch on a virtual reality screen as Kryten's search for an antidote is manifested as a western setting where Kryten is a sheriff who has to fight the four horsemen of the Apocalypse - Death, War, Pestilence and Famine.