An owl hooted softly above them, making Gemma jump. For the first time, she felt the deep twitchy pull of fear, as if it was something physical inside her body, running around inside the nerve endings. She recalled the photos on the whiteboard of Ralph Allerton’s bloated corpse, and then what Emad had reported the mental nurse saying – the one who’d shown him Catherine Brown’s room with its Blu Tack pockmarks on the wall: how the staff thought it was funny that the woman had so many photos of a band she hated.

A woman so violent that she’d been considered a serious risk to herself and others for the best part of thirty years, with a rap sheet of violence as long as her arm. Not someone you’d want to have hating you.

‘Not gonna lie, Emad,’ Gemma admitted softly. ‘I’m a bit scared.’

There was a pause, then Emad replied, ‘Me too.’

‘She’s a nutter, this Brown woman, isn’t she? Sounds like she might’ve been responsible for the attack on Meredith last time, if she’s got someone on the outside helping her.’ Gemma felt a huge pang of worry for both Meredith and Pete. If it really was Brown, going to the trouble of escaping, presumably for the sole reason of having another pop at Meredith, they could be in serious trouble.

‘Sounds like,’ agreed Emad. ‘But all this might not be anything to do with her.’

‘Really glad you’re here.’

‘Me too.’

They walked fast in silence for a couple of minutes, the only sound their panting breaths, until the lawns ended abruptly at a wooden fence. There was a gate set into it a little way along.

‘Through here, I think. Shit, look.’ She pointed the phone at the gate, where a padlock had been sawn open and was swinging by its hasp. ‘This isn’t looking good…’

They broke into a run, down a narrow gravel path twisting through more trees, until suddenly they arrived at a small, detached single-storey mock-Tudor building.

‘Round here,’ Emad whispered, and they tiptoed towards the entrance, trying to silence their laboured breathing.

Gemma could feel her heart banging so hard in her ribcage from both exertion and fear that she thought it would be audible for miles around. The heavy Victorian iron door, set with stained-glass panels, was ajar, but all seemed dark and silent inside.

They crept in.

‘It’s an old swimming pool,’ Emad said in wonder. ‘Wow. No idea this was here. Why is it so far from the house?’

Gemma didn’t answer. She shone her torch around. ‘Hello? Meredith? Are you there? Are you hurt?’

No reply, just a faint scuffling from somewhere around the edge that made them both jump again.

‘Mice,’ whispered Emad.

‘Or rats,’ said Gemma darkly. ‘I hate rats.’