A sudden movement of heads in the crowd, mouths opening, reminded Ava of the synchronisation of a flock of birds. She directed her binoculars back up to the top of the tower block. Janet Monroe had taken it up a notch and was suddenly much closer to the edge of the building, leaning over. For a moment, Ava saw herself up there, pushing her luck to its limits at Tantallon Castle.

There were two more camera crews recording footage now and Monroe was fully engaged in conversation with Charlie Packham. Ava picked up her radio again.

‘Unit Six, you’re go,’ she said.

Outside, one of the undercover officers was about to start a rumour that Janet Monroe was a neighbour of his. He would reveal limited information, give a different surname for her, but make sure the TV crew got sufficient for any interested party to be able to pursue her. Sure enough, the media began closing in on one particular area of the crowd. The officer would refuse to give an on-camera interview, purportedly out of ‘respect’ for his neighbour, but the details he gave would signal the beginning of the end of the operation.

‘Check the online newsfeeds, Tripp,’ Ava said. ‘Let’s make sure the information we’ve planted is filtering through, then we can move Janet on to being talked down.’

It took another ten minutes before the first updates came through online, but the undercover officer had done a good job. Janet Vargas – her maiden name – had been depressed ever since splitting from her partner. She lived a few roads away from Pennywell Gardens, probably in flats she could see from where she stood right now. The reports had already labelled her vulnerable and distressed. Impressive, given that not one journalist had spoken to her directly.

Through the radio, Ava gave the final order.

‘Signal end to Monroe then move in.’

Holding her breath as she watched, Ava could see Monroe flailing her arms. The agreement had been that she never got within tripping distance of the edge. Enough lives had been lost in the previous month without Monroe adding hers to the total.

‘Please,’ Ava could hear the counsellor saying, ‘I really don’t want anyone to get hurt. Think about your baby. She needs to grow up knowing her mother.’

‘She’ll be better off without me,’ Monroe cried.

‘No. No, she won’t. There’s never going to be a replacement for you. Just take my hand,’ the counsellor implored. ‘No tricks, I promise. Just let me reach out to you.’

On top of the building, Janet Monroe swayed dangerously near the edge.

‘Get back,’ Ava ordered her, uselessly.

There were gasps from the crowd. Someone screamed, another began praying loudly and, above it all, Ava could hear laughter.

‘Who is that?’ she demanded.