She had a lead on me of about twenty metres. I screamed out for her to stop but of course she ignored me and ran for all she was worth.

The street was busy and pedestrians stared at us both, startled. Those who got in our way were unceremoniously shoved aside. As I ran my face was clenched with murderous fury. I had never in my life felt so worked up. So driven. So determined.

I was totally consumed by a visceral hatred for the woman I was chasing. I had to stop her causing any more pain and suffering. And I had to make her pay for the damage she’d already done.

I could hear sirens shrieking from all directions, getting closer, drowning out the other city sounds.

My breath rasped in my throat as I hurtled along the road. But I wasn’t gaining ground. The muscles in my legs burned as I hammered my feet on the pavement. The woman was fit and fast, and I was terrified I was going to lose her.

But I knew that if I did I would never forgive myself. This might be the closest we would ever get to bringing her down. I was the only thing that stood between the bitch and freedom. If she managed to give me the slip then she would find it easy to disappear in a city with a population of nearly nine million people.

Suddenly she veered to the right and sprinted across the road between the slow-moving traffic. A young man coming the opposite way was pushed to the ground, and a bus driver had to slam on his brakes to avoid running him over.

Somehow I managed to keep pace with her, although it was a struggle. I could barely breathe now and my chest felt as though it was going to explode. But a voice in my head was screaming at me to keep going. To ignore the pain. For Aidan. For mum. For my dead colleagues. For Dave Prentiss’s child who would never know his father thanks to the she-devil up ahead. And for the life she had effectively ripped out of my own womb.

After another half minute of hot pursuit my perseverance paid off when she tried to jostle her way through a cluster of tourists and lost her balance, stumbling into the road.

Luck deserted her again because at that very moment a motorcycle was overtaking on the inside and it struck her side-on with a sickening thud. She was thrown back onto the pavement and into the group of tourists. I heard her cry out and saw her hit the ground.

The group dispersed and I rushed forward, my wheezing breath loud in my ears. Suddenly I was looking down on the woman they called The Slayer. And I felt a pang of disappointment that she was still conscious and not covered in blood.