Does your story drag when you reread it, despite a well-conceived plot? You may be having trouble with dramatic tension. A feeling of tension in the reader is vital to building suspense because it keeps the reader from feeling complacent.
Reader complacency is the enemy to tension. A reader can still feel complacent — and bored — even when faced with the fastest, most action-packed plot.
How can this be?
The complacent reader knows what is going to happen. So even when the character is surprised, the reader is not. Predictability is the enemy to dramatic tension.
It is not necessary for the character to feel the tension, so long as the reader feels it.
After all, the character isn’t the one reading the book, turning the pages, making the decision whether or not to put the book down or stay up through the night. Tension in the reader overlaps with — but is not identical to — tension in the viewpoint character.
You can fight complacency with uncertaainty. Not uncertainty in the character (though that can help) but uncertainty in the reader.
Surprise the reader.