Growing up in Scotland and spending my early twenties living in New York, when it was still very much a city gripped by the crack-cocaine epidemic, I've seen some unpleasant things.
I've seen one human being kicked unconscious by another human being. I've walked out of a neighbourhood bodega on 110th street to see dead bodies strewn across the sidewalk, victims of a gang-related drive-by shooting. I've had a knife pulled on me. I was witness to a Marine getting a bottle cracked across his skull when he tried to stop a homeless man dragging a woman into her apartment to rape her. Running down the stairs to see what was happening I actually thought he'd been shot because the crack of bottle on head was so loud, he wasn't moving and there was so much blood. (Note to readers: the would-be rapist absconded, the intended victim was very shaken but thankfully unharmed and the Marine made a full recovery.)
Beyond first hand experience, I count among my friends men who've served in some of the most dangerous places on earth. My brother-in-law started his career as a rookie patrol officer in one of the more dangerous divisions in the Los Angeles Police Department. Andy Carmichael, my technical advisor on all matters security-related, is a former member of the Royal Military Police close protection unit with service in Afghanistan, Northern Ireland and Sierra Leone.
In other words, it takes quite a lot to send a chill down my spine.
But that's exactly what happened some four years ago after I fell into a chance conversation with a well dressed couple who were enjoying a drink in the bar of the Four Seasons hotel on the banks of the Danube in Budapest.
I was there for a long weekend with my wife and daughter, who was then four-years-old. My daughter, bored by the grown-up discussion, was hiding under our heavy winter coats which were draped over a club chair.
That was when one half of the couple my wife and I were talking to leaned over to me, her gaze fixed on my daughter, and said, 'whatever you do when you're in Budapest, don't take your eyes off her for a second.'
It struck me as strange thing to say until she, and the man who was with her, a Belgian, explained that they were part of the narco-trafficking division of the United Nations, in town for a conference. And that, while we all grow up hearing tales of children vanishing into thin air and think of them as just that, stories, child abduction is a reality. For profit in some cases. In other cases there are far darker motives.
I thanked her for her advice, we finished our drink, and left. Needless to say my poor daughter wasn't allowed more than six feet from either of her parents for the rest of the trip.
The event stayed with me and it threw up several questions, all of which were about to be explored on prime-time television when Madeleine McCann was abducted while on holiday with her parents in Portugal.
The one question that plagued me the most though was this - you're a stranger in a strange land and the unimaginable happens. Who do you turn to? The obvious answer would seem to be the local authorities, but we all saw how that went for the McCann family.
So as I researched the answer to that question, I stumbled upon the world of private close protection security. It was a world that instantly fascinated me because the more I looked into it, the more my pre-conceptions evaporated. Yes, there were plenty of what my now friends would call 'thick-necked twats' working as bodyguards to C-list celebs, but there were also companies who you could turn to if you found yourself with a problem that conventional means couldn't solve, and, of course, if you had the money.
In the months before the McCann case exploded into the public consciousness, I sat down to write a television script about a child who is spirited away while her parents are visiting Eastern Europe. It wasn't a bad effort but it had one major failing. I didn't know who the men and women charged with finding this child were. They felt like photocopies of characters that I'd seen in movies or read about in books.
I wanted to get under the skin of the so-called bullet catchers, to really understand how they could place themselves in situations where there was a clear and present risk to their lives. Where the end-game for some of them is death.
So, through a desire to know more, and a sense that reading books and trawling the internet wouldn't give me any truly satisfying answers, I enrolled on a three-week residential bodyguard training course based in the UK and Eastern Europe. My family thought I had finally cracked, my colleagues ditto, friends queried my wife about 'whether I was okay?', but in 2006 I got on a plane at Dublin airport and headed for a former army camp in Wales.
To say it was an interesting experience would be like saying that Muhammad Ali could handle himself in the ring. I was about to step further out of my comfort zone than I'd ever done before.
It was the beginning of a journey which would change my career, my life and how I look at the world...