Fifteen minutes. Alison Vlasich sighed, got to her feet and looked through the wired glass of the locked door. The old man was still talking, the officer writing out a report. She clenched her fists and walked out.

Ten minutes later she arrived home again. The driving rain had soaked through her anorak, and her shirt was wet. She put on a fresh blouse, picked up the phone and dialled 999.

‘It’s my daughter,’ she said. ‘She’s been abducted.’

Half an hour after her call two people came, a stern-looking woman in uniform and a man in a suit. They both seemed very young. She was so flustered by now that she didn’t catch either of their names the first time, and had to ask them to repeat them: Police Constable Sangster and Detective Sergeant Lowry. They all sat down and she gave them her daughter’s name, Kerri, and age, fourteen last birthday in July.

Why had it taken her almost forty-eight hours to report Kerri missing? She bit her lip and twisted her fingers and tried to explain, the effort almost more than she could manage. The flat was empty when she’d got home from work on Monday evening, two days ago. She’d looked in Kerri’s bedroom and seen that her daughter had changed her clothes after school, and had then presumably gone out again. When Kerri hadn’t appeared by seven that evening, Alison Vlasich had had another look in the girl’s room and realised that she had taken her pyjamas and her frog bag.

‘Frog bag?’ The woman constable looked up from her notepad.

‘It’s shaped like a frog, bright green, and when she wears it it looks as if there’s a big frog sitting on her back.’ Alison began to cry quietly.