Murder has marked us all as Cain's children: Cain who when the earth was young slew his brother with the jawbone of an ass and hid in the forest until God hunted him out, grasped his head and gave him the assassin's mark. We must be his children, mustn't we? If Cain, the son of Adam, is father to us all, then we must all bear his mark.

I see my chaplain sniffing as if he has smelt something foul: his prim lips are pursed, that cherry nose wrinkled. The trouble with him is his nose is too near his codpiece! Never trust short-legged men – the gap between their brain and their buttocks is too close for comfort.

Ah, well, so we are all Cain's children. In fairness, I must confess that's not an original thought. Michael Nostradamus, Catherine de Medici's fortune-teller, once told me that whilst I was hiding in Paris from a group of assassins who wanted to take my head but, as I keep saying, that's another story.

A strange man, Nostradamus! In his secret chamber at the Castle Blois he had a famous mirror. If you looked into it, you could see the future. Catherine de Medici, voluptuous, murderous Catherine – Madame Serpent as I call her – used to spend days staring into it.

Nostradamus also claimed he had dreams which foretold the future: demons who appeared to him at night, their black eyes filled with blood, huge scrolls in their fists, the written records of the sins of men from the first day to the last. Nostradamus said they kept unrolling these scrolls and there was no end to them. No end to the terrible and bloody murders of men.

I agree with him for Murder has haunted my life and still plagues my dreams. Oh no, I am not an assassin myself but I have spent my life tracking them down. Now I, too, have the same dreams as Nostradamus: strange, merciless devils, faces twisted with rage, teeth showing over their lips. They belong to the blackest darkness for they are the lost souls of murderers.