The Doctor and Benny arrive on a planet, investigating the last words of a dying man and attempting to prevent a disaster. However, they're quickly arrested by Adjudicators Chris Cwej and Roz Forrester, but soon have to team up against a greater evil that the Doctor has faced before.
This novel contains examples of:
- Airstrip One: The Earth Empire has renamed all Earth's cities "Spaceports". Original Sin is mostly set in Spaceport 5 Overcity, which seems to be London.
- Arc Welding: The villain of Original Sin is retroactively claimed to have been at work behind the scenes in a number of the Doctor's earlier adventures.
- Brain Uploading: The Big Bad is hundreds of years old thanks to this.
- Covers Always Lie: The Doctor is wearing a tie in the cover art, despite the text referring to his cravat. He's also being arrested by Cwej and Forrester — but Cwej isn't in the form of a giant walking teddy bear, as he is in the corresponding scene in the text.
- Cranial Processing Unit: Lampshaded. The Doctor decapitates a hostile robot, and then muses how fortunate it was that the robot's designer had put the brain in the head.
- Fantastic Racism: Roz is initially prejudiced against aliens, but she still tries to treat them fairly; later revealed that her memory has been tampered with as part of an attempt to cover up the bigger conspiracy
- Gesundheit: Benny says "Bless you" when offered a tisane by Provost-Major Beltempest. Beltempest doesn't realize she was making a joke, and explains what a tisane is.
- I Have This Friend...: Lampshaded.'Doc, there's something I need to ask you... It's — well...'
'It's about this friend of yours,' the Doctor prompted.
'Yeah. Right. He's got a problem.'
'Friends always do.'
- It Is Pronounced "Tro-PAY": Inverted by Chris Cwej. His surname should be pronounced "Shvay", but because everyone pronounces it "Kwedge" he's decided to go along with it. When they first meet, Roz Forrester has gone to the trouble of learning the correct pronunciation, and he has to correct her to the incorrect pronunciation.
- Meaningful Rename: Done by an entire species, the Hith, after losing an extremely unpleasant war with the Earth Empire. The two Hith met in the course of the book are named "Homeless Forsaken Betrayed And Alone" and "Powerless Friendless And Scattered Through Space".
- Mega-Corp: Initec. Its specialty is robotics, but it also produces weaponry and spaceships. Its proprietor has significant behind-the-scenes power.
- Noble Bigot with a Badge: Adjudicator Roz Forrester, a black woman who is totally prejudiced against aliens, but also one of the few Adjudicators in Spaceport 5 who actually makes any effort to help them.
- Not So Different: The Doctor is trapped in a room with homicidal maniac Zebulon Pryce, who claims that the Doctor's Technical Pacifist nature is not so different in practice from Pryce's usual behaviour, and challenges him to prove otherwise.
- Old Cop, Young Cop: Forrester and Cwej.
- Pig Latin: The Doctor has to work with some military types to stop an alien starship that's leaking dangerous radiation. When he has to go and retrieve the TARDIS, knowing that the military probably want to seize the ship for their own purposes, he gives their commander a message to pass on to Benny: "Ashtray the ipshay".
- Properly Paranoid: The Doctor is becoming an old hand at this conspiracy business.Paranoia is just another word for a heightened appreciation of how badly the universe wants to get you.
- Reading Your Rights: The Adjudicators' version of reading your rights is pretty close to "you have no rights" anyway, but Roz Forrester still adds her own spin:I am obliged to inform you that your words, gestures and postures are being recorded and may form part of any legal action against you. Under the terms of the data protection act 2820, as amended 2945, I am also obliged to inform you that you and any appointed legal representative will be able to purchase a copy of all recordings upon payment of the standard fee. I am obliged to tell you that, but I won't bother. Just don't piss us around.
- Salt and Pepper: Chris Cwej and Roz Forrester, Adjudicators from 30th century Earth (that time period's police). In a variation on the trope, Chris was the wide-eyed rookie, while Roz was the older, jaded and cynical veteran.
- Shout-Out: A chapter introduction mentions the planets Murtaugh and Riggs IV.
- Significant Anagram: "Interstellar Nanoatomic ITEC" is an anagram of "International Electromatics". Lane cheated slightly by declaring that in the Future, "ITEC" will be a common company-name suffix like "Ltd" or "Inc" (standing for "Independent Terran Empire Corporation"). Still pretty impressive he was only four letters out though.
- Space Police: The Adjudicators.
- They Fight Crime!: She's a bitter, cynical veteran cop who doesn't know she's had a memory wipe, he's a naive but enthusiastic rookie who happens to be body-modified into the form of a bear. They fight crime in the future and in SPAAACE!
- Titled After the Song: Original Sin is a reference to the INXS song.
- Transferable Memory: Memory editing is a thing in the future setting. In the course of the story, Roz learns that one of her own most painful memories is a fake (she had it done to herself; the truth is even more painful).
- Under City: Spaceport Overcity Five was built on top of London, and what's left of the old city is referred to as the Undercity and occupied only by criminals and people who can't afford to live anywhere better. (In a variation on the trope, the Undercity isn't buried: the entire Overcity hovers above it on Anti-Gravity engines.)
- Unreliable Illustrator: Original Sin, which introduces new companions Roz Forrester and Chris Cwej, features several internal illustrations to help readers get an idea of what they look like. For this reason, they depict Chris as he usually looks, which (due to a plot point involving Magic Plastic Surgery) is not actually what he looks like in some of the scenes depicted (including the one on the cover).
The audio adaptation additionally contains examples of:
- Writing Around Trademarks: Either because of rights issues or simply because Kevin Stoney is dead, Tobias Vaughn remains unnamed in the audio adaptation. It's still very obviously him, though.