Clara burst into tears. ‘I just can’t …’

‘Come over,’ Zoe’s voice was firm. ‘Right now. Put some things in a bag, get in the car, and come.’

Zoe lived in a small, end-of-terrace house in East Greenwich with her husband Adam and their new baby, Oscar. Clara knocked and stood on the doorstep, listening to the sound of Oscar wailing from somewhere within, and tried to suppress a fresh, dizzying panic, gripping on to the wall to steady herself. Come on, Zo, she thought desperately. Please answer. And then the door opened and there was Zoe, the sight of her, the relief of it, almost undoing her. She was dressed in dungarees that were covered in something which looked like porridge, her auburn curls tied up in a messy topknot, her face lined with tiredness, her hand reaching out to her as she said, ‘Clara, oh sweetheart, come here, it’s all right; it’s OK.’

Later, in the warm and untidy living room, its floors strewn with baby paraphernalia, Clara finally stopped crying long enough to look up and see six-month-old Oscar watching her from his mother’s lap, his big brown eyes wide with fascination. She gave a shaky laugh. ‘Sorry, Ozzy, you must think your godmother’s a loon.’

‘Oh well,’ Zoe said mildly. ‘Makes a nice change from your own dramas doesn’t it, Oz?’ She leant over and, squeezing Clara’s hand, said, gently, ‘Tell me what’s been going on.’

So Clara told her, about Luke’s cheating, the conversation with Sadie, the blue van and the CCTV footage, the strange woman who lived upstairs. As she talked she felt the knot in her chest gradually loosen fraction by fraction. Despite their lives taking such different directions, despite relationships, careers, motherhood, and all the other myriad experiences that over the years had slowly altered both the people they’d once been and the friendship they’d once had, there still remained between them the closeness and ease they’d known since primary school, and for the first time since Luke had disappeared she felt her churning panic subside a little.

‘Holy fuck, Clara,’ Zoe said when she’d finished. She shook her head in disbelief. ‘I don’t know what to say.’

Clara rubbed her eyes tiredly. ‘I know he’s a cheat and a liar and all the rest, but I can’t walk away from it all and let the police deal with it. I can’t let Rose and Oliver cope with all this by themselves. And I can’t just turn off my feelings for Luke. He’s in danger and I don’t know what to do to help him. I don’t know how to help his mum and dad, who’re going through hell, I don’t know what the fuck to do about any of it.’