We've all seen this moment in a movie. Amateur sleuths, whether it's a kid or a suspicious neighbor or a wary spouse, want to do some digging and figure out what a person is really up to. The first thing they'll do is check the date book. There will be a mysterious appointment penciled in. A trip to the appointment at the right time will reveal unknown secrets.
Another way this trope appears in movies is with the deceased. After a character dies, it's impossible to find out more about what his or her life was like without detective work. A check in the date book will reveal the secret fight club she was attending, or the dog shows he'd been competing in with his poodle that no one knew about. Character - revealed!
All this is a reminder that the date book - or its modern equivalent - is a treasure trove of character. You may not keep a paper date book anymore - I know I've moved to iCal, and even my parents have moved on from the same black leather calendar they used to get every year and now use Google or Yahoo calendars. All the same, a paper or electronic date book is where our lives truly unfold. Date books tell stories about characters' lives, just as they're used for detective work in movies. They tell people who we care about meeting and when; who we're dating; who we're keeping secrets from; what hobbies we have; and what we don't want others to know. Date books are as intimate as diaries in many ways.
Using Date Books as Plot Devices
Do you keep a date book? To learn how to use one in fiction, try studying your own for starters. Note what you actually write down and the idiosyncratic way we take notes when we know we're the only ones likely to read them. Notice abbreviations and errors. What do you keep in your head without writing down? What goes in the date book?
Introduce tension through discovery
Of course, our own date books aren't mysteries to ourselves; the source of suspense comes from a character's attempt to understand another. This struggle is fundamental to many stories; the date book is just a convenient modern tool for drawing that tension out. In order to make it part of your plot, give us something we don't know about in the date book. Let us try to puzzle out a note's meaning as though it were a hieroglyphic. Let the appointment come up; let your sleuth character go to the appointment, but not figure out immediately what it might be. Above all, let the date book act as a window into another person's identity. For a large part, we live secret lives, letting others see only minimal, carefully controlled slivers of what we really are doing and thinking. Let a tool like a date book do the miraculous, and look beyond that sliver.