There is an essential need to up the ante in a mystery – if there’s a murder, is there the threat of a second or a third? Could the investigator be at risk? Someone near and dear to him or her? If there isn’t the threat of a murder, could it be that the villain will “get away” with his or her plan? What effect will that have on the hero, the investigator or innocent bystanders.
We must increase the conflict and tension to have a satisfying denouement that the reader can believe in and be happy about. We can have conflict between characters if the investigator and the villain come face-to-face. Or the villain and another victim. Or the investigator and authorities, if the detective isn’t law enforcement.
We can also increase the tension with setting and atmosphere. A dark, deserted urban setting is much more intimidating than a peaceful country trail on a sunny day with dozens of hikers around. A dwelling with no power versus a homey bed & breakfast with a grandmotherly owner. A storm (whether wind, rain or snow) versus the perfect sunny day with puffy clouds.
I find it a “fun” part of the process to increase the tension and conflict – maybe because there are so many options. How do YOU increase tension in your stories to make them more enjoyable for your readers?