I've read a book.
I'm not telling you which one, although I'm likely to write about it elsewhere. This is because it contains a problem, and one which has affected far too many books I've read lately.
It's the bad guy. Commonly known as the antagonist. The one who has a goal opposed to the protagonist, whatever it might be: anything from world domination to stealing his girlfriend to besting him in dominoes.
Nothing wrong with this. Every story needs one. There has to be a conflict, even if it's only the protagonist wrestling with himself (think "story of a recovering alcoholic") or with the weather (think "polar explorer").
One thing that's often missing when beginners write is the antagonist's motivation. "He's bad" won't do. "He's a killer" is only marginally better. "He's a Nazi" is edging into acceptable, because that's sort of shorthand for a whole host of disreputable attitudes and actions. "He's a psychopath" is a possibility, although that's too often used as a hand wave for excusing any irrational behaviour that pushes the plot in the desired direction.
But for a serious writer, that won't do. You'll have to have reasons for the antagonist to be bad. The murderer had a motive - say, jealousy - and the Nazi had a horrible childhood: now we're getting somewhere.
This story I've read now had a bit of that. The villain was quite carefully crafted, with a deep trauma which made some of his quirks understandable, possibly even reasonable, after a fashion.
But come the end, this all got lost. It was a straight shoot-out, with the protagonist eventually outwitting the bad guy. The effect was to make the antagonist's backstory seem plastered on, added in editing.
Why was this so?
The writer (and quite possibly the writers of very nearly all thrillers I've read this year) had forgotten one fundamental fact.
From the viewpoint of the antagonist, they were writing a tragedy.
And the tragic part of a tragedy isn't just that it ends badly. It's that the unhappy ending is inevitable. It was built into the setup from the beginning. It was part of the antagonist's character to be a person who could not succeed at the task at hand. The downfall of the antagonist must happen because of something that's intrinsic to him (or her, if you're e.g. writing a romance, where the supermodel must fail to steal the protagonist's boyfriend because she's unable to realise that she might not be irresistible to all men, which is possibly the worst example I've come up with for half a decade but it's past midnight now).
You can't have the hero defeat him in a straight shoot-out. You'll have to have the antagonist defeat himself in a shoot-out. Over-confidence would have done the trick in the one I read, even if it might have seemed a bit cheap after all the setting up.
But ideally, the protagonist should, after arranging the situation to his satisfaction, only have to watch everything fall apart.
I did that. Promise.