Our objective this afternoon was to securely position the control box into the Marine Invertebrates room and test that the radio range would have no interference.

A class-load of overexcited two-year-olds aside, it should be a straightforward mission.

The other parents, mostly mothers, were talking among themselves. Thirty-six kids, covered by nearly as many adults. I wondered whether it was the health and safety dictating ratios or if many of the parents had taken the afternoon off specially to accompany their little ones on the big museum day out. I stood beside Frederick as Florence and Gigi whispered and giggled to each other in front of us. Gigi was wearing a red mackintosh and floral-embroidered jeans. Her brown hair was tied back in pigtails. One was already half coming out. She was so excited for this trip. Every time she looked at me her dimples shone as she grinned the biggest grin. I was so glad to be here.

With Yvonne leading the way, holding a yellow flag on a stick high above her head, we all headed inside the museum.

I leaned towards Frederick. ‘Last Tuesday Daddy Pig apparently went to a conference in Birmingham.’

‘Tuesday . . .’ Frederick was a quiet for a moment. ‘No, there was nothing on the schedule. He was still in the office when I left around seven p.m.’

‘It could’ve been a meeting with the headhunters. I’ll get G and Pixie to check his credit card and the CCTV records. We might be able to pick him up leaving the building.’

‘Has Hattie rethought giving the Pigs trackers? I can easily fit them.’

I shook my head. ‘He thinks it’s too big a risk. If any of them discover a tracker they’ll know we’re closing in and that they’re under suspicion. Tenebris may know we’re hovering but they mustn’t know how close.’

I looked down at Gigi and Florence still giggling together. I wondered if I could get Eight to set up a trip to the Aquarium next. Much better going during the week and missing all the weekend crowds.

‘Hello, there.’ A young blonde teacher with a clipboard came up to us. ‘Now, are you Florence’s parents? Or Gigi’s?’

‘I’m Florence’s father.’

‘And I’m Gigi’s mother.’

‘Oh, right, sorry. I just presumed . . . Apologies!’ she trilled.

‘We work together,’ I offered.

‘How lovely. Great. So you have your two covered. And I’m going to allocate you Milo and Jack as well.’ She made a couple of ticks on her clipboard and motioned towards two boys who were chasing each other up and down the corridor. ‘Milo! Jack! Come here, please.’ She beckoned them over to us. ‘This is,’ she peered at our name labels, ‘Alexis and Frederick, and they’ll be looking after you on this trip so make sure you do exactly as they say.’