'No Struggle, no panic. Only a push of breath, hands gripping the sheets, twisting them. The knife had been well honed...'

As Dr Helen Wilkinson stands over the body of her husband Edward it is just as she had imagined it so many times before. He looks calm, asleep almost, for his eyes are closed, his hands folded neatly on top of the fresh sheets. And yet something isn't right: in her fantasies there was never so much blood.