The novel was written by Rob Grant on his own. It follows on directly from the second Grant Naylor novel, Better Than Life, ignoring Last Human which was by Doug Naylor. As well as Backwards it contains elements of the episodes Dimension Jump and Gunmen of the Apocalypse.
When they arrive, the crew examine Starbug to find most of the landing jets missing and the underside a mess of rust and badly-repaired damage. Unable to understand how it happened, but realising that on the backwards Earth they will need the landing jets to perform a take-off, they begin searching for the missing jets. While searching Kryten discovers the body of a hillbilly, who has been killed with a pickaxe. He panics when the corpse begins returning to life and removes the pickaxe from the man's chest. Once the man leaves, Kryten replays the incident 'forwards' and realises he was responsible for killing the man, a serious breech of his programming not to harm humans. Overwhelmed by guilt, Kryten shuts himself down.
Having only found one landing jet in terrible condition, and with Lister busy repairing Kryten, the crew's attempt at a reverse landing fails and they trapped on htraE, having missed their flight window. Kryten is eventually fixed and he informs them they will have to wait 10 years for another opportunity to leave.
Ten years pass and while Kryten and Rimmer are physically unaffected, the reverse time of backwards Earth means Lister and The Cat are now 15. During the wait, The Cat becomes a virgin during a bizarre sexual encounter with a female cousin of the 'un-murdered' hillbilly, and the crew busy themselves reburying the landing jet they found and 'un-repairing' the damage to Starbug, which begins to become less rusted but more damaged as the reverse landing window approaches. When the time arrives, the crew begin the reverse landing, sending the underpowered ship scraping backwards over a nearby mountain, a process which repairs much of the damage as several landing jets leap from the forest and reattach themselves. With the craft still out of control, they are unstruck by a missile from the American 'Star Wars' defence system, which had misidentified Starbug as a threat. With the remainder of the damage repaired, the crew leave for their own universe to rendezvous with Red Dwarf, but find it to be missing without trace.
Discovering the remains of Holly, the Dwarf crew learn of the Agonoid threat, but with food and fuel supplies on Starbug severely low they have no options available but to head for Red Dwarf regardless.
At the same time, in a parellel universe, Ace Rimmer is preparing to test pilot a ship capable of crossing dimensions. The brave, heroic and charismatic Ace (a complete contrast to the neurotic Rimmer) arrives in the Red Dwarf timeline, materialising so close to Starbug as to severely damage both ships. Coming over to Starbug to help with repairs, Ace deduces it may be possible to rig up his ship to take the Dwarfers home.
The Agonoids meanwhile are fighting for the right to torture and kill the last remaining human. Djuhn'Keep, the most ruthless Agonoid, succeeds in jettisoning the others into space, but notices to his chagrin that one, Pizzak'Rapp, is headed directly for Starbug. Pizzak'Rapp attempts to break into the ship, but Ace sacrifices himself to send the Agonoid into space.
Meanwhile, Djuhn'Keep arrives on Starbug, just as the oxygen supply fails. Horrified at losing the opportunity to torture Lister, Djuhn swiftly repairs the Oxygeneration unit. Kryten bazookoids the freshly repaired hull, causing a breech which sucks the Agonoid into space. The crew then learn that Djuhn has infected the ship's NaviComp with a computer virus (the Armageddon virus), causing them to be locked on course towards a nearby planet. Kryten decides to deliberately contract the virus to create an antidote, cryptically telling the crew to 'watch his dreams' before becoming unresponsive.
Entering Krytens dream-state through a VR machine, the crew find themselves in a replica of an old Western, with the various characters representing Kryten's characteristics ('Wyatt Memory', 'Billy Belief', etc.), being threatened by 'the Apocalypse boys', representing the virus. Kryten's consciousness is represented by the town lawman, Sheriff Carton.
In order to buy Kryten time, the crew (Rimmer, Lister and The Cat), adopt personas from a VR Western game, Streets of Larado. With impeccable skills in fighting, knife-throwing and shooting provided by the VR machine, along with the knowledge that they can't be injured, they attempts to take on the apocalypse boys to distract them from destroying the town or killing Sheriff Carton. However, the virus spreads to the VR machine the crew is connected to, sealing them into the artificial reality, removing their 'special skills' and allowing them to feel pain. The crew clash with the Apocalypse boys regardless, and are subject to terrible injuries. However, Kryten has enough time to complete the antidote program just as the Apocalypse boys gun him down.
With the Apocalypse boys vapourised, Lister and The Cat return to reality to find the virus has killed both Kryten and Rimmer, destroying their mechanical components. Since the VR machine only simulated their injuries, they find themselves unharmed. With the virus gone, they are able to control the ship, but since it has been accelerating for several hours there is not sufficient fuel left to avoid hitting the planet. Cramming into Ace's one-man ship Wildfire, which he had programmed for another jump, they cross dimensions, finding themselves in a timeline where Kryten and Rimmer are still alive, but their own counterparts died playing Better Than Life. As they dock with the alternate Red Dwarf, Lister reflects that while this isn't home, it might be close enough.