Lucy approached the address the control room operator had given to her; it was a lovely detached house with a secluded drive. Everyone seemed to have nice big houses except her, and she felt more than a little envious. Her home with George had been similar to this, maybe even bigger. Patrick lived alone, as far as she knew; she’d have thought one of the new beachfront apartments would have been more his style.

She got out of the car and began the walk up his drive, not even sure if he would be home. As she rounded the bend she saw the plain silver divisional car: so he was here. Skiving, no doubt; the man didn’t have a full day’s work inside him. She went up the steps to the house and peered into the bay window. The only piece of furniture in the big room was a sofa. There were no coffee tables, sideboards, pictures or ornaments. There were several large packing boxes stacked against one wall. He was either moving in or moving out. She lifted her hand and knocked on the front door; the sound echoed throughout the house. She waited a couple of minutes, then decided to go and have a look around the back.

The garage door was three quarters of the way open so she stopped and peered inside. It was pretty dark in there. Ducking under the door, she stepped inside to see if he was in there faffing around – these big houses usually had a door which led into the main building. She looked at the white Ford Transit van parked in front of her, with the words ‘Drain Busters’ printed on the side. That was odd; maybe he shared the house with someone else because as far as she knew Patrick had only ever been a copper. She couldn’t imagine he had the energy or the inclination to be running a business on the side. It would explain a lot, though, if he was knackered because he was working two jobs. That could be the reason why he was just floating along at work without actually doing anything. The only thing was, drain cleaning wasn’t his style.

Her foot connected with something on the floor and she kicked it across the room. Following after to retrieve whatever it was, she noticed a huge metal drum against the back wall. Her phone began to vibrate in her pocket. She tugged it out and whispered, ‘Hello?’

‘It’s Col again. I’ve had a look at those print-outs you gave me and I don’t know if this is stupid or not.’

‘Try me.’

‘Well, Peter Sutcliffe was the most infamous killer of the seventies, Bible John for the sixties, Peter Manuel for the fifties. I think he picks the most famous killer from each decade and copies them.’

Lucy ran the information through her mind. ‘Oh my God, yes. You’re right, that’s so obvious. Why did I not think about that?’

‘Sometimes it takes a fresh pair of eyes to see what’s in front of you. Anyway, I think if he is working his way backwards he’s going to be emulating the most famous killer from the forties next. I mean, this stuff is complete genius in a terrible kind of way. You’ve got to give it to him: it’s different, shocking and not blatantly obvious what he’s doing. I mean, it’s taken us long enough to figure it out.’

Lucy looked down to the floor to see what it was that she’d hoofed across the garage. She saw an empty plastic container with the words ‘Sulphuric Acid’ blazoned across it. Next to that was a discarded, crumpled, black-and-white cupcake case. Just like the ones on the cooling rack in the kitchen at the Martins’ house. She felt her blood run cold.

Col continued. ‘Well, I’ve done some research and I reckon the killer he’s going to copy next is John George Haigh.’

Both of them spoke at the same time. ‘The acid bath murderer.’

She began to back out of the garage, her heart thundering so loud in her chest that she couldn’t think straight. She whispered to Col, ‘I think I’ve found him.’

Before she could say anything else, she felt a strong arm wrap around her neck from behind as it got her into a chokehold. She dropped her phone as she lifted her hands to try to release the pressure on her neck. Her attacker stamped on it, ending the call and shattering the screen. Within seconds the pressure on her neck had become too much and her vision began to blur. The garage went black and she collapsed to her knees, unconscious.

Scooping Lucy into his arms, he carried her into the house. He hadn’t wanted to hurt her. He liked her too much, although he had been shocked to see her walking up his drive after their run-in that morning. Now he’d changed his mind. She’d had the audacity to come to his house and confront him, alone. Who did she think she was? He wasn’t going to pass up the opportunity to kill again. Besides, he had no other option; she’d figured him out. He couldn’t let her live – it would be game over. After he’d taken care of Lewis, he would deal with her.

* * *

Mattie unlocked the cuffs, wondering if Lucy would ever speak to him again after this. ‘Toby, this is important and you have to admit it’s a bit odd that you turned up out of the blue at the boss’s house with vital information.’

Toby, who was rubbing his wrists, looked up at Mattie. ‘Lucy thought it was good information? She didn’t laugh about it or call me a weirdo when she told you?’

Browning spoke up. ‘Nope, she said you were on to something and she was very grateful for your input.’

‘Then why did you want to arrest me?’

‘Because we thought that only the killer would have that kind of inside knowledge.’

Toby’s nan was shaking her head and tutting.

‘Are you two for real? Anyone with a vested interest in serial killers would have made the connection. I’m afraid this is partly my fault; I’ve always had this morbid fascination with them. Toby’s mum used to bring all these true crime books home from the library where she worked for me to read, and I guess Toby picked up on them. I’m afraid you are positively barking up the wrong tree. If you give me a list of the relevant dates I can almost guarantee that Toby would have been at home with me, if he wasn’t away on training or at work. He doesn’t go out much, do you?’

Toby’s cheeks burned red as he shook his head. Mattie’s phone began to ring and he answered to a frantic Col.

‘I’ve lost touch with Lucy. She gave me that stuff to look at about serial killers from back in the day. I phoned her up to tell her that I thought the killer was going to copy another murderer soon and she whispered that she thought she’d found him. Then her phone went dead and now it’s going straight to voicemail.’

‘What? Bloody hell, two hours ago we thought it was Toby. Only it’s not because we’re here with him. Jesus, not again. You have to find the new boss, get him to authorise a cell site analysis of Lucy’s phone so we have something to go off. Did she say where she was going?’

‘No – she left in a bit of a foul mood, though. I saw her come out of the boss’s office, but the DCI was nowhere to be seen.’ Col was out of breath because he’d run straight from his desk to Tom’s office. ‘He’s still not here. I haven’t see him for ages; I don’t know where either of them are.’

Mattie ran his hand through his hair, his eyes wild. He looked at Browning, who understood what had happened from the gist of the conversation and the panic in Mattie’s voice. ‘We have to go now. I’m sorry about the mix-up, Toby; we’ll get this straightened out later.’

They began to run towards the front door and he followed. ‘I’m coming with you.’

Browning turned to look at him. ‘No you’re not, you’re a civilian – you might get hurt.’

‘I might be able to help.’

Mattie shook his head, but let him follow them anyway. Right now he’d take whatever help he could get. Toby clambered into the back of the car.

‘Where are we going?’

‘To check Lucy isn’t at her house.’

‘She won’t be there. It sounds like she’s inadvertently stumbled upon whoever it is you’re looking for. So where might she have gone? Did you have any leads whatsoever?’

Mattie looked at him in the rear-view mirror. ‘You’re the expert. Your guess is as good as mine.’