After she fed Noah and cradled him in her arms until his eyes fluttered closed, she placed him in his Moses basket. The guilt at giving him formula milk rather than her own was all-consuming. She was letting Noah down. Taking her mobile, Louisa scrolled through her list of numbers until she reached Sandy’s. She pressed the button to make the call to her health visitor. The answer machine kicked in after only a few rings. In a forced upbeat tone, Louisa left a message requesting that Sandy give her a ring to arrange a home visit as soon as she was able. Hopefully Louisa hadn’t come across as desperate. She didn’t want Sandy coming over today; she had to clean the house first.

With that job done, Louisa checked her Messenger app to see if Oliver had bothered to reply yet. Nothing – even though a tick beside her message informed her that it’d been ‘seen’ at 13.45 on Tuesday. She paced the room, her mind frantically considering what reasons he’d have for not replying once he’d seen it. The resulting conclusion was that something else must’ve happened: like Melissa had been found and he simply didn’t need Louisa anymore.

Louisa huffed and got up to make another coffee. So, if Melissa had been found and he no longer required Louisa’s help and wasn’t going to contact her again, why had he gone to such lengths to look her up in the first place? That had happened before Melissa went missing; he hadn’t needed her then. Unless …

Louisa’s mind raced. No one remembered seeing Melissa at the party. Or at least, no one she’d spoken to. That in itself was odd. But even the notion of Oliver concocting a story to make it seem like Melissa had been there when in fact she hadn’t made Louisa uncomfortable.

You can help me, like I once helped you. Those words. How he’d spoken them. They turned her insides to liquid.

The ring of the doorbell pierced through the quiet house.

‘Good morning, Mrs Cullen.’ The uniformed police officer who spoke was standing back from the threshold of her door with a stern-looking woman by her side who didn’t make eye contact – she was busy giving the house a once-over, her dark eyes travelling to the pathway that separated Louisa’s house from her neighbour’s and that led to the rear of the property.

‘Morning. What can I help you with?’ Louisa’s insides quivered. There was only one reason they would be at her door.

‘I’m DS Farley, and this is my colleague, DC Patel. We were hoping to have a chat with you today about the night of Friday, fifteenth of March. You informed us at the station on Monday it was your birthday party that evening?’