The prologue of my fourth book is only 259 words long and in those few paragraphs one of my characters is kidnapped.
The key to writing a kidnapping is to make it a surprise to both the character and your reader. Have your character be doing something normal such as feeding their cat, taking a nap, or making a cup of hot chocolate. It can be anything that distracts them. Describe them in the act of what they are doing. Their attention is focused on their task and they aren’t aware of anything else but the cat bowl.
Then in the next sentence or paragraph mention to your reader that someone is coming up behind them. Now describe the attack. Is there a struggle? Does the kidnapper hit their victim in the back of the head, use drugs, a taser, tape and rope, or a gun and a threat?
Definitely make sure to tell your reader what the victim is feeling, thinking, and everything he/she does during the course of the kidnapping. A kidnapping isn’t a kidnapping unless there is fear, because nothing is more terrifying than being attacked, over powered, and forcefully taken to God-only-knows-where by a stranger. Make your reader afraid for your character.
Chapter One of my book continues the terror from the prologue with my character coming out of unconsciousness. I describe her surroundings, the fact that she is bound tightly by rope, and her fear when she learns who her kidnapper is.
For more on how to write a kidnapping go to: http://writewithfey.blogspot.com/2013/01/writing-about-kidnapping.html