Once again, I’m copying from Carolyn Wheat’s list of 16 differences between mystery and suspense. You can find this list in Wheat’s book HOW TO WRITE KILLER FICTION. It’s also reprinted in T. Macdonald Skillman’s book WRITING THE THRILLER. But no matter where you read it from, the list is an excellent resource.
Difference number eight is this: Readers of mysteries are looking for clues. Readers of suspense are expecting surprises.
In a mystery, part of the thrill for the reader is trying to figure out whodunit before the final reveal. Nothing beats the elation of thinking I’ve solved the crime before the protagonist has. Or the “a-ha” moment when I realize I was cleverly lead astray but have now uncovered the truth. Nothing’s worse than getting to the end of a mystery and realizing the author cheated by leaving out a vital clue, and I had absolutely no chance of solving it on my own. The best mystery writers embed all the vital clues into the story so carefully that sometimes they don’t look like actual clues. The old hiding-in-plain-sight trick. But no matter how they do it, the reader feels like an amateur detective for that short period of time.
Suspense books might or might not have a mystery involved, but the clues aren’t the important part of the journey. It’s the surprise. The unexpected. The gibberish-inducing fear. The nervous giggle. The nausea-inspiring, sleep-with-the-light-on-for-three-days terror. The white-knuckled grip on the book and you can’t relax enough to put the book down even though it’s three a.m. and the kids will demand breakfast at seven. It’s the emotional roller coaster you go through every time you pick up a Stephen King or a Michael Crichton or a Robert Ludlum book.
In suspense, it’s all in the emotions.