James butted in. ‘We’re playing king of the castle and Matthew’s dad is helping him. You’re bigger than his dad so we might win.’ They both jumped up and down, slapping his legs like rhythmically challenged drummers.

‘I’d love to stay and continue the chat, sis, but duty calls,’ Porter said with a shrug.

‘This isn’t over,’ she called after him.

He knew he’d taken the coward’s way out. Knew he couldn’t dodge the issue for ever. He waded carefully through the ball pool, convinced he’d step on a submerged child any moment, and up into the heart of the soft-play. A small boy wearing a fierce expression began launching plastic balls at him from the top of a plastic slide. Matthew, he presumed. Tom and James charged fearlessly past him and began clambering upwards. Porter followed them, his promised two minutes turning into ten, then fifteen. The worries of the previous week were a long way away, at least for now. When he finally clambered back out, he realised that he was actually enjoying himself, smiling. That didn’t happen often enough these days.

Styles swung by Saint Agnes’ Catholic School first thing Monday morning on his way to the station. The buildings were shrouded behind twin barriers of trees and grey railings. Groups of chattering children swarmed through the gates, leaving parents waving at their backs. Styles identified himself to a teaching assistant shepherding the kids through the front door, and was pointed inside to the front desk. The receptionist Styles spoke to answered in a lethargic tone, but that quickly changed to flustered when he explained he was a policeman. The poor woman stammered an apology and went off to find Mr Palmer, the teacher who headed up the alumni association responsible for coordinating events for former pupils.

Mr Palmer peered at Styles through glasses as thick as a telescope lens when he came through the door two minutes later, nervy as if the receptionist was playing a prank on him by saying a police officer was waiting for him. He listened without interruption while Styles explained why he was there, and promised to email across a list of pupils from Natasha’s year, along with the contact details they had for them.

Styles thanked him and headed off to meet Porter at the station. When he arrived, he saw Porter slouched in his chair, arms crossed, staring out of the window as he slowly dragged a thumb back and forth across his stubble.

‘Simmons in yet?’ asked Styles, reaching for his cup.

‘No, she’s running late, but I spoke to Gibson. Sounds like there’s going to be some action tonight. Seems our inside guy is due to pick up a fresh consignment later this evening. He’s going in wired up, but there’s going to be a team outside.’