So, let’s talk about how to structure a thriller. Two things before I begin:
This is not prescriptive. That is, I’m not telling you how to structure YOUR book. I’m simply giving you what the elements are for a thriller, so that, should you find that your book would benefit from this structure, you can revise some into the book to improve it.
Thriller structure can be used for more than thrillers. I’ve seen it used in women-in-peril romances, Jim Butcher uses elements of it in his urban fantasy (not the whole of it, though), F. Paul Wilson mostly uses it on his books (mostly because the ending often isn’t), and you can use at least part of the structure in books that you want to give a tighter and faster feel to.
Now that that’s out of the way, let’s begin.
A Thriller structure is called that because it — duh — is mostly used in thrillers. That is, it is used in books where the forces of good race the forces of evil before something horrible can happen.
A note on that horrible thing: it has to fit the book. If you’re using thriller structure for a children’s board book (Heavens knows why. I’m not responsible for the crazy things YOU do) the terrible thing might be that the little boy/girl loses a cookie. If you’re using thriller structure for a spy thriller, the terrible thing might be the planet-killing bomb going off.
You begin a thriller by making it clear how evil the antagonist is and what kind of mayhem he can bring.
Of course you don’t show him setting off the planet killing bomb, but you might show him setting off a country-killing bomb and enjoying the results.
Depending on what type of book you’re writing, this section might or might not show the character’s identifying characteristics. If your book slants traditional mystery, the identity is occluded, of course.
Thriller structure requires a sense of urgency. This means some way you give equal time to the bad guy’s plans and the main character’s efforts to defeat them. Whether this is through letters the villain sends or through scenes that show the villain setting the trap, is up to you.
To tighten the screw:
Every book has timing devices. I.e. “she must be married before–” “He must find the formula before”.
In the thriller the timing device is often made explicit. It is not unusual to have the countdown clock literally on screen or in the title of each chapter, as it counts down to irrevocable doom unless our plucky hero…
The climax: will often be just before, or even just after the final countdown (but before the bomb explodes/disaster happens.)
To further tighten the screw:
The villain must do more heinous things, and they must escalate, so that the reader FEELS the urgency of stopping him.
There must be a fight. You can’t get away with a soft ending in a thriller. there has to be a fight and your character has to pay for his victory somehow, even if just in tiredness and abrasions.
For further reading I recommend: