Every protagonist has a motive. Without a motive, the protagonist would be perfectly happy sitting on the couch at home eating potato chips and watching TV. A skilled novelist knows she has to do something to shake things up in the protagonist's life. We have to upset Ms. Protagonist's balance of happiness so she crosses the "adventure threshold" to get her comfortable stability back. Here's where Tension-Building Technique #3 comes into play. It's what Donald Maass in his excellent Writing the Breakout Novel Workbook refers to as "raising the stakes."
Raising the stakes happens every time you introduce a situation that makes it more important for your protagonist to restore balance to her life.
Suppose Katie's brother has just been murdered, and her Type A personality won't let her rest until the killer is brought to justice. The police have written off Bill's death as a suicide, but Katie knows Bill better than that and decides to look for his murderer on her own. In the meantime, however, new evidence arrives, implicating Katie in the crime.
How important has it now become for Katie to solve the crime? The stakes have now been raised. But wait a second! While Katie is evading the police and getting ever closer to discovering the real killer's identity, Mr. Murderer now discovers what she's up to and decides to finish her off.
What started out as an emotional tragedy has now ballooned into a life or death situation. Mix in a lot of unanswered questions and a few chapter-ending cliffhangers, and you might just have your readers hooked.
I like to use a "rotating story" to give my students hands on practice with raising the stakes. Each student creates a character, a motive, and a goal which she then hands off to a second student. Student #2 looks at the character's goal and decides what would make it twice as important for the character to accomplish it. Now the story moves off to Student #3 who must triple the importance of achieving the goal.
For an in-depth look at how to master this and other tension-building techniques, I recommend Donald Maass's book. It's a valuable resource for any writing teacher or author and provides multiple examples of tension at work.
Speaking of motives and goals, check back next week to see how these elements can be used to heighten a story's tension.