The bomb in the last chapter.
This is a perfect answer to a hard question. It nails it like the Romans nailed Jesus.
One way to keep a reader hooked is to let them know in the beginning that there is a bomb in the last chapter ready to go off.
You could do it Micheal Bay style and have a bomb that is activated for no reason and have it do a five minute countdown for twenty minutes of the film. (I know this is the fifth post to pick on that movie, but it deserves it.) It's better (better than a Micheal Bay movie, I've got low standards) to have a ticking bomb be a symbol of change.
I'll grab another bad film. One that really shows the checklist of things to put in an action thriller. Dirty Dancing. I realize Dirty Dancing either wasn't an action thriller or the writer didn't know the definition of action thriller. But it does have all the elements perfectly laid out.
It introduces the ticking bomb in the first scene. Baby says her life will change in two weeks that they are at the resort. Tick Tock.
She meets the hero, Swayze, who has a conflict. He wants to do Dirty Dancing (which is tame these days) but must follow the rules. She is conflicted herself she wants to help everyone, but her dad wants to protect her.
She does a dance montage, (action films need a montage) and her clothes get skimpier. The entire time we are reminded that she must learn how to dance quickly as the clock is ticking.
Finally the bad guy wins. In this case by being good, but misguided. The moment of peril is at hand. Will Baby be in the corner forever? Will Swayze be able to do the final dance?
Naturally the hero comes in and cuts the green wire of the bomb by saying, “Nobody puts Baby in a corner.”
Evil is defeated, or at least the Dad realizes he was under the wrong impression. Same thing.
Although Dirty Dancing is downright funny in how bad the dialog is. How simplistic the plotting is. A number of other things. It still sells and rents out. That's because it follows an action plot better than a whole lot of action films these days.
Every story has a ticking bomb at the end. That moment that changes the characters lives forever. If the characters aren't moved at the end of the story, why should the reader be?
The job of the writer is to make sure the reader can hear the bomb ticking in the background. If they can the story will tick along with it.
By Darrell B. Nelson author of I KILLED THE MAN THAT WASN'T THERE