‘I’m a psychologist. I peer into people’s souls.’ Sara looked up and Elizabeth’s gentler smile was fading. ‘When you have a minute,’ she continued, ‘look up the word “sociopath”. See if it summons any ghosts.’

Elizabeth turned on her heel. After a few seconds she stopped and turned back. ‘It’s that he might come for her – that’s what scares me.’ Without a further word, she disappeared round the side of the house. A woman, thought Sara, who has come to dislike saying goodbye.

On the train back to London, her attempts to read notes, papers, anything were disrupted by memories and thoughts. She submitted and, staring through a window at the passing fields, allowed them to flow.

The anonymous text message to Marion had shaken her to the core. Even though the tone differed from the curt anonymity of the texts to herself, the sender surely must be the same. She recalled those messages. It was true that one colleague, Patrick, was not what he seemed. Could the text when she was in Blackburn just be saying: I’m here, I’m with you, keeping an eye on you, keeping you safe? And now the apparently helpful text to Marion’s phone. Who was pulling her strings? What was their motive? Both questions unnerved her. It was more than that. She was frightened – because she understood she was no longer in control, and perhaps never had been.

An unsought image of the pregnant Marion’s bruised wrists led to images of charred limbs – and then back to a sublime, innocent moment of her life before all of this. The evening of July the 6th 2005 when she, her cousin Salman, his wife Nusrat, and their new baby – with the baby’s two-year-old brother fast asleep along the passage – were finishing a celebratory supper at the couple’s basement flat in north London.

The surprise was sprung over ice cream and a chocolate sauce that matched the baby’s eyes.

‘We’re naming her after you,’ said Nusrat.

‘What?’ Sara replied, incredulity giving way to delight. The baby’s parents were paying her the greatest possible compliment.

Sara.

‘You never had a brother or sister,’ said Salman. ‘So we thought you could be special to each other.’

‘Thank you,’ she replied. ‘That means so much to me.’

She examined the tiny, two-week-old ball of new life; creased cheeks, half-opened eyes, wisps of dark brown hair. Earlier she’d watched the mouth feeding greedily from her mother; how could a being so fragile pulsate with such energy and hunger?

There was a further reason to smile. That morning, in Singapore, it had been announced that London had beaten Paris to host the 2012 Olympics – billions of pounds of investment, a new Olympic city, new stadiums; the greatest show on earth would be coming to the home city of the small group supping around that kitchen table. The baby would be a sevenyear-old girl when the games arrived.