One of the coolest thriller specs I read recently dropped just enough bread crumbs that I couldn't stop turning the pages.
I scratched my head & asked, "How'd he do that?"
Roger Ebert explains how one new release did it in today's review today of a S. Korean thriller, The Chaser:
"The story is an exercise in audience manipulation, especially with the corruption and incompetence of the police. The director, Na Hong-jin, knows exactly what he's doing. Like Hitchcock, he gives the audience precisely enough information to be frustrated. It is obvious to us what the characters should be doing, but there are excellent reasons why it isn't obvious to them. If you can contrive that in a screenplay, you have already surpassed the level of the usual modern thriller."
Get that? There's an "EXCELLENT reason why it isn't obvious" to the characters.
It must be plausible why they pick the wrong fork in the road.
It must be plausible why he narrowly misses catching the good guy.
WHAT I'VE LEARNED: Aristotle says that the choices must be plausible. Need I say more?
The review: http://rogerebert.suntimes.com/apps/pbcs.dll/article?AID=/20100127/REVIEWS/100129976/-1/email_headlines