Episode one from the 2005 series, RT 54:40.

Some good, some bad, and a few just plain evil. Individually, we each tell as many as 15 porkies a week, and are on the receiving end of even more. And yet despite the fact lying is everywhere, few other human traits are so little understood.

Exposed attempts to unravel some of the mysteries surrounding this most powerful and seemingly instinctive human trait.

In exploring just why it is we tell lies, John Marsden meets Donald Bickerstaff, a man who lied himself into a $15m fortune, and finds out from his victims just what it's like to have your life turned upside down by someone unable to feel guilt.

In learning how we can protect ourselves against the dangers of deceit, John also meets Beth Shannon, with the ability to spot over 90% of lies, and discovers precisely how to beat that most famous of lie detectors- the polygraph.

And, in attempting to discover whether liars are born or made, it turns out that the secret lies within a portion of our brain no bigger than an almond. Straight up.