Everything changes when you find out who you really are.

Over the past few months, I've lost a bit of weight without trying and suffered a few dizzy spells, both symptoms I put down to delayed shock and lingering grief. Losing your little sister is going to take its toll, mentally and physically.

The driver who killed her confessed and was convicted, but he's going to be released from prison any day now.

Soon he'll walk free but my teenage sister will still be dead.

I'm coming to grips with that knowledge when my world turns upside down.

I volunteer to take part in a study of the brains of violent criminals. I'll be the control sample of a 'normal' brain. But then the doctor calls me into his office.

We need to discuss your scan . . .

I feel lightheaded as he breaks the news: I'm not normal. My brain shows all the classic abnormalities of a high-level psychopath.

Later as I take a sip of white wine in a city bar, my head is crowded with possibilities. Dark thoughts. Twisted opportunities.

Maybe it's time to embrace my secret self.

Maybe finding out I'm a psychopath is the push I need to exact revenge . . .

What would you do?