‘Your mother turned up here a while ago,’ he said, before I could get a word in. ‘She’s been in tears and is fucking terrified.’

My mum had met Dave Prentiss, of course, from the time he came to the school. So it didn’t surprise me that she was getting even more worked up.

I couldn’t lie to Aidan so I told him that we’d received another message. This one had simply said: You now know that it wasn’t an empty threat. Interestingly the latest text had not been sent to him or my mother, which probably meant that only the task force detectives had received it.

‘I won’t be coming home tonight,’ I said. ‘I have to go back to the office.’

Aidan drew in a loud breath. ‘So what if the killer turns up on our doorstep? Shouldn’t we be given some kind of protection?’

‘That’s something I’ll be pushing for, Aidan. I promise. In the meantime don’t answer the door to anyone you don’t know.’

‘But this is crazy. We shouldn’t be living in fear like this.’

‘I realise that and I can assure you that everything possible is being done to find out who’s behind this.’

His voice cracked with fury. ‘That’s the type of thing you say to the media, Laura. Not to me.’

DCS Drummond was sitting next to me in the back seat of the patrol car and I was sure that he could hear what Aidan was saying.

‘I’m sorry, Aidan,’ I said, wishing I’d held off calling him until I was back in the office. ‘But please stay calm and try not to worry. It’s extremely unlikely that the killer will strike again tonight.’

‘And is that supposed to reassure me and your mum?’

‘Look, I really do understand how you must feel,’ I said. ‘All I can do is to ask the local station to send a patrol car round to watch the house. I’ll call them straight away.’

‘Well, I appreciate that, Laura and so does your mum. She’s staying here for the night.’

‘That’s good. But I have to go. You should both try to get some sleep. I’ll ring when I can with an update.’

We said our goodbyes and I severed the connection.

‘I’m sorry about that, guv, but my boyfriend is really worried.’

‘There’s no need to apologise,’ Drummond said. ‘He’s right to be worried. We all are. And arranging for a car to watch the house is a good idea.’ He pulled out his phone. ‘In fact let me do it for you. I’ll call control and get them to send marked cars to the homes of all the detectives, including my own.’

‘I thought your wife was away in Scotland, guv,’ I said.