No matter how many times I read this novel, one scene always makes my blood boil. It's a scene that some people adore, the sequence where Ace and Justine debate theology and Justine suggests that the Doctor isn't deceiving her by suggesting he's a sorcerer, he's deceiving Ace by suggesting he's an alien scientist with a time machine. Ace finds herself wracked with doubt, unable to find purchase for her whole worldview...
Except that this is Ace. She met the Doctor on another planet. The previous novel, she actually met other members of the Doctor's species. Four novels ago, she met Hitler. The idea that she'd doubt the Doctor's claims of being an alien time traveler just because snotty teen Justine said so is not just stupid, it's insulting. But even worse, the whole idea that Ace is a skeptic who would tell Justine that there's no such thing as demons is fundamentally unsound. Ace knows there are such things as demons. She stood against Morgaine in the final battle for Arthur's legacy, holding Excalibur within a chalk circle while the Fae Queen summoned the Destroyer. She is not going to tell Justine that magic is garbage, she's going to tell her that she's seen magic and Vincent doesn't have it.
For another author, this scene might be an understandable lapse. It's Doctor Who, after all, and it's hard for every writer to remember every story. But Cartmel helped to create Ace. He was script editor on 'Battlefield'. He has no excuses. For Cartmel to make Ace into a strawman skeptic just so that he can tear her apart for this one scene betrays the fundamental fact about Cartmel: He does not care about coherency. Not narrative coherency, not consistency of characterization. Everything he does is designed to service the aesthetic of the story, with Cartmel setting up one set piece after another with no more than lip service paid to how they actually work together as a story.
Don't get me wrong, that actually can be an effective way to write. (Although it's certainly a better way to script edit...looking back on his time on the series, it's pretty clear that he gave the writers "big moments" like the Cheetah People on horseback or the Neanderthal delivering a copy of the Times to the prisoner in the cell, and relied on his writers to work them into a narrative.) But if you're going to utterly subsume the narrative to the aesthetic and create something that works more as prose poetry than as a plotted novel, the important question becomes: What's the aesthetic?
And the answer is, "An utterly hokey eco-fable so humorless and self-righteous as to almost flip over to 'inadvertently hilarious' but not quite make it, leaving you trapped and utterly loathing every second of it as surely as if you were stuck in an elevator with that annoying guy from your PoliSci class for a weekend." If Ric from 'The Young Ones' were to write a Doctor Who novel, this would be it. It could not feel more like it was written by a smug sixteen year old who thought that they learned all the answers to humanity's problems from old Dead Kennedys albums if it actually came with an 'Eat the Rich' T shirt.
In 'Warhead', humanity's problems with pollution don't stem from neglect, they're the work of a cabal of Secret Rich People who control all humanity and plan to turn themselves into robots. The kids are all video-game addicted psychopaths who love their violent TV. Every problem a dystopia might have (or rather, might have had in 1985...this book was published in 1992 and already felt like it was out of date...) is whipped up into a shrieking froth of panic and despair just so that the Doctor can stop it by killing a rich guy. That's honestly the whole of the story.
Which has two major flaws. One, the Doctor is portrayed as a ruthless murderer with a flair for the melodramatic. Two, the entire slide of the human race into poverty, amorality and slow death by pollution and eco-catastrophe can be halted solely by killing one rich guy. I'm honestly not sure which of those two things drags the novel down more.