She was lying on her side and struggling to breathe. Her eyes were dazed and startled at the same time, her mouth twisted into an ugly grimace. Clearly she was in pain but her injuries weren’t visible.

I took out my ID and waved it in the air. ‘I’m a police officer,’ I shouted while panting for breath. ‘Stay back and give us space. This woman is under arrest.’

As I spoke she rolled on her side and reached for her bag, which was lying next to her. It made me think that she might have a gun so I dropped to the ground and flung my body over hers.

‘Forget it, bitch!’ I screamed into her face. ‘Your number’s up and you’re nicked.’

I forced her onto her back and she gave a groan of agony. She wasn’t so pretty now, or so threatening. The Slayer had been subdued and she looked pathetic. I could barely believe that she was the woman who had terrorised the city. The cold-blooded killing machine from Mexico. Her heart may have been made of stone but her body, as it turned out, was as fragile as mine.

I searched her bag and sure enough there was a pistol inside with a silencer attached to the barrel. I had no doubt that it had been used to kill WPC Campbell.

As she looked up at me her face curled into a frown.

‘I know you,’ she said. ‘You’re that detective.’

I nodded, blinking furiously at the sweat stinging my eyes.

‘That’s right,’ I said. ‘You tried to kill me and you messed up. You shot my man instead. And the fact that I’m the one who’s collared you has made my day.’

She tried to lift her arm to strike me but it was obviously hurt and the pain of movement made her yelp.

‘You don’t deserve to live,’ I told her. ‘But you deserve to fucking suffer. And believe me you will.’

There was so much I wanted to do to the bitch, so much harm I wanted to inflict. But I couldn’t because people were watching and the sirens were fast approaching.

So instead I leaned over and whispered in her ear. ‘You know what’s really funny, you evil fucking cow. It’s that in the end it was a ruddy motorbike that brought you down. I find that beautifully ironic.’

It turned out she had a broken arm and a fractured thighbone. So in that respect she was fortunate. The motorbike that ran into her could have caused so much more damage.

She was taken to hospital in an ambulance with an armed police escort.

I watched from the pavement as they sped off. I was drenched in sweat and my lungs were aching from exhaustion. But at the same time I was feeling mightily pleased with myself.