It’s often important, I think, to build up the level of suspense in a novel.  When the reader doesn’t know what’s going to happen, s/he will tend to want to read more, and will become more emotionally involved.  That emotional involvement usually means that the reader derives greater enjoyment from the book.

On the one hand, when the reader can predict exactly what’s going to happen, s/he will probably judge the book to be ‘boring’.  And, on the other hand, if the author uses too many devices to heighten suspense, or puts too many  twists and turns in the plot, the book (and the author) lose credibility.

Life is unpredictable.  We all know that.  So having some surprises in a book we read seems natural.  We all enjoy a good surprise, and a bad surprise can be quite stimulating, particularly if it isn’t real, and it’s happening to someone else (not us).

What kind of surprises could there be?  There are romantic surprises: will he or won’t he get the girl?  Court room surprises: will she or won’t she be acquitted?  There are business surprises: will it succeed or fail?  Sports surprises: does he or does he not win the medal?  And I’m sure you can think of at least a dozen other categories of surprises.

Another point to bear in mind is that surprises  don’t have to be binary: yes or no; win or lose.  Sometimes a surprise will come completely out of ‘left field’.  For example, you’ve been reading about Michael and Claire, who’ve just started dating.  The author leads you to wonder whether Michael and Claire will become a couple.  Sometimes you think ‘yes’ and at other times ‘no’. All of a sudden, Michael’s cousin, Jack, enters the picture, and sweeps Claire off her feet.  Then, you wonder what Michael is going to do.  Will he brood?  Will he try to punish Claire in some way? Or will he become the best man at the wedding?

So what are some of the devices an author can use to heighten suspense?

• the structure of the plot can lead to uncertainty in the reader’s mind.  For example, in a murder mystery not enough evidence comes out that we know George is guilty.  Besides, there’s some evidence that Norman might be the guilty one.
• what the characters do or say about an issue can influence our thinking.  What would you think if Norman hid a piece of evidence?
• it’s not just the principal characters who influence things.  Suppose Margaret tells the police that she saw George do it, but you suddenly learn that Margaret and Norman have been having an affair.
• mistakes can be made.  This is a device used frequently in operas.  For example in Il Trovatoreby Guiseppe Verdi, Count di Luna orders the  execution of Manrico who is his rival for the love of Leonora.  The Count finds out too late that Manrico was actually his brother.
• miscommunications can take place
• places can be different than what they seem at first
• times and relationships  can be confused
• and so on

I don’t know whether you have been watching Montalbano, the Italian series about the Sicilian detective Montalbano.  It’s currently running on BBC4 with English subtitles.  Montalbano is a very handsome, macho, detective who has an absolutely lucious girlfriend, and he always ‘gets his man’ because of his brilliance and his intuition.  My wife and I enjoy watching it.  I like the girlfriend.  My wife likes Montalbano and being able to watch a program in Italian.  We are both amused by the Sicilian culture on display: stupid Carabinieri (Italian police), for example.  But neither of us can follow the plot.  It has so many nuanced twists and turns that, unless you’re a professional crime detective watcher, it’s not worth following.