But for Hunted, the new series I created for the BBC, I've moved away from science fiction to the spy genre, which is my favourite in all of film and television.

There are some obvious reasons for this.

Spy stories provide plenty of opportunities for action and suspense - things motion pictures can deliver with unique effectiveness.

But I think the real appeal of the spy genre is much deeper.

By definition spies are duplicitous. They appear to be one type of person when they are actually someone else altogether.

They pursue one agenda while pretending to serve another. A spy simply cannot be trusted.

To varying degrees the same can be said of all of us, spies or not.

We all present a face to the world that is not exactly the person we are inside. Because part of us always remains hidden, none of us is truly knowable - not our parents, siblings, spouse or friends.

It's not surprising we all yearn to be surrounded by people we can trust. And fear betrayal.

Melissa George as Sam Hunter during filming

That for me is what spy stories do so well. Spies live in a world of deceit and distrust. Their stories externalise our deepest fears.

By design Hunted plays on these fears in the most intimate way I could imagine.

Sam Hunter suspects that she has been betrayed by the man she loves. She must expose herself to mortal danger, knowing she can't trust him or anyone else.

Of course Sam is more than an embodiment of our collective fears. Brilliantly realised by Melissa George, she is a unique, complex, contradictory character with a dark and troubled past.

I am neither a spy nor a woman and yet I find it very easy to identify with Sam. I suspect many audiences will too.

Complicating Sam's situation is the brave new world in which she we now live.

Over the past few decades espionage has become increasingly privatised. Sam doesn't work for MI5 or MI6 - she works for Byzantium, a private security firm dedicated not to defence of the realm but to serving the interests of its clients.

These clients' identities are not revealed to operatives like Sam which makes identifying who might want her dead - and why - even more difficult.

Researching this world proved less difficult than you might imagine.

Business is booming - there are now thousands of private security firms operating all over the globe.

And while they keep secret their client lists they were very happy to talk (with names withheld) about the work they do.

I collaborated with a team of talented writers for six months on the stories for Hunted.

We devised a complicated web of deception with lots of action, suspense, and plot twists and turns.

But at the heart of it all we tried to never lose sight of the character of Sam, who anchors this dangerous world in a deeper emotional truth.

Frank Spotnitz is the executive producer and lead writer of Hunted.

Comments made by writers on the BBC TV blog are their own opinions and not necessarily those of the BBC.