Despite its claim of twenty-four-hour service, the storage warehouse was closed for the night.

A sign outside said: For on-call duty manager phone 07831 560516. There was a security light above the front entrance, but otherwise the building and car park were in complete darkness.

‘Don’t really like leaving you here, darlin’,’ said the cabbie, who had introduced himself as Jim. ‘Doesn’t seem right.’

‘I’ve got a colleague on the way over. I’ll be fine,’ Rachel reassured him.

‘How about I hang around as your wingman till he gets here? I’ve always fancied being one of the Sweeney.’

Rachel left Jim sitting in his cab with the interior light on and pulled out her phone. It was a toss-up – did she summon the manager or call for a support vehicle? She remembered Brickall’s diktat on deploying belt and braces and decided to do both. First she summoned a tactical unit, who would be able to break into the place and search it. Then she called the manager, who answered after a couple of rings.

‘No problem: I’ll be there in three minutes.’

‘Make it two.’

And he was: a cheerful young Turkish man wearing a padded coat over a T-shirt and tracksuit bottoms.

‘I’ll need to check the records on the computer; give me a sec.’

Rachel shifted from foot to foot while he switched on the lights and waited for the system to boot up.

‘Everything okay, guv?’ shouted Jim from the cab. She gave him a thumbs-up.

‘Harper… Harper. No, we ain’t got no unit reserved to Harper.’

‘Or Hutchins?’

He searched again, whistling as he flicked slowly through the spreadsheet. ‘I’m going to have to ask you to hurry.’ Rachel couldn’t help snapping. She glanced out at the front car park but there was still only Jim there. ‘I’ve reason to believe there could be a child in one of your storage units.’

The man’s eyes widened. ‘You’re kidding!’

‘No, I’m not.’

‘Well there’s definitely no Hutchins, sorry.’

‘Are you sure?’

‘One hundred per cent, look.’ He swivelled the screen to show her.

Rachel could feel sweat running down her back, despite the chill in the office. Brickall had landed on this place, but how many other businesses with the capability to store a suitcase could there be within a five-mile radius of the airport? Dozens? Hundreds? This was a child-sized needle in a metropolitan haystack. Lola Jade had been drugged and imprisoned for over eighteen hours now: time and oxygen could already have run out.

‘How about Brown?’ she asked.

‘Got a couple of Browns, but they’ve all been here long-term. House contents and that.’

Her heart racing, Rachel performed a mental scan of everything she knew about Michelle. Then it came to her: something that had been on the divorce paperwork. Her maiden name: Kenny.

‘Try Kenny.’

‘Yeah, we’ve got a Kenny. Opened the account yesterday. Wanted one of our smallest units.’

‘Get the key.’

They ran down the aisle between numbered steel-fronted units until they reached Unit 148. A few feet away, Rachel heard vehicles skidding to a halt on the gravel, footsteps running.

And there it was. The second purple suitcase.

She tipped it onto its side, trembling as she fumbled for the zip. Two officers in tactical gear appeared in the doorway, and she heard another, familiar voice shouting into a phone for an ambulance.

Curled up in a foetal position, wearing unicorn pyjamas, her skin a sickly purplish grey, was the missing child.

‘Oh Lola,’ whispered Rachel. She brushed tears from her eyes and stroked the short, damp hair, blonde roots starting to show through the brown dye.

Brickall darted forward and pushed Rachel aside, pressing two fingers against the child’s neck. On her ear lobes there were faint dot-like scars where her ear piercings were starting to heal over.

‘Have you got a pulse?’ asked one of the officers.

‘I’m not sure.’ Brickall lifted the girl from the base of the suitcase, laid her on the floor and started chest compressions.

Somewhere outside, there was the insistent whine of an ambulance siren; more footsteps.

Rachel reached for Lola Jade’s wrist, aware that she was holding her own breath. And there it was, the faintest thread.

‘She’s alive. Just.’