It seemed a long time before the light stopped falling, its beam swinging through the water to dazzle him. Cooper closed his eyes against the shock and the roar of water in his ears. He panicked when he realized he couldn’t tell which way was up, and he began to thrash his arms and legs. He seemed to hit something, or something hit him, he couldn’t tell which. The cold was already striking through to his soaking skin.

He opened his eyes again, and saw that the light was receding now, drawing away from him into the gloom. He seemed to be trapped by something, his clothes caught up on some heavy, rusty object under the water. He thought he must be sinking, and he thrashed harder. Just when he felt he couldn’t hold his breath any longer, his head suddenly burst clear of the water and he gasped in a deep, ragged mouthful of air.

Dazed, Cooper realized that the collar of his jacket was being gripped by someone, and he was being dragged vigorously towards the side of the channel.

A deep voice laughed close to his ear.

‘Bezopasno li e pluvaneto tuk? Are you sure it’s safe to swim here?’

37

Sunday, 30 October

The following afternoon, Fry was sitting alone in the CID room at West Street. Everyone else who was on duty today had joined the search for Luanne Mullen. Most of them were expecting the divers of the underwater search team to have made a find by the time they’d finished dragging the channels of the mill goyt. Unless the child’s body had been swept out into the river and was miles away from Matlock Bath by now.

Fry was thinking of her conversation with Brian Mullen early that morning. Same hospital, different ward. A Mullen who looked sicker and paler than ever.

‘I always thought the adoption in Bulgaria was the wrong thing,’ Mullen had said to her. ‘I mean, I love Luanne to bits, and I wouldn’t have parted with her, once we’d got her. I couldn’t have taken her away from Lindsay. But I never thought it was right. It felt dodgy to me. I knew there’d be trouble. But Henry kept pushing and pushing, and Lindsay always went along with what he said.’

‘I see.’

‘It was all illegal, wasn’t it? False documents, and everything?’

‘Yes, I’m afraid so.’

Mullen had lain back, exhausted. ‘I’ve never been involved in anything illegal before. Never. I knew they’d catch up with us.’

‘Who?’

‘I never knew who they’d be exactly, but I was sure someone would come one day, to take Luanne back. It was like we were living on borrowed time. And once that Rose Shepherd turned up again, that was the last straw. But no one else could see what I was afraid of. They told me I was being stupid.’

‘Is that what you were having arguments with Lindsay about?’

‘No, we never had arguments, I told you. We disagreed about some things. But I was right, wasn’t I? They did come.’

‘Possibly. But you have no idea who these people might be?’

‘Somebody from Bulgaria, that’s all I can guess at. They’ve got Luanne, haven’t they? Have they taken her back there?’

‘I really don’t know, sir. I’m sorry. But we’re doing our best to find her.’

It hadn’t sounded convincing, even to Fry herself. Mullen had just looked even more sick.

‘Can I ask you about something else, Mr Mullen?’ she’d said.

‘What?’

‘Your next-door neighbour, Mr Wade.’

‘Keith Wade? He’s a good neighbour. He’s always kept an eye on our house. I know he can seem a bit rough, and his wife walked out on him, poor bloke. But Lindsay saw a lot of him during the day when he was on late shifts, and he always took an interest in the kids.’

‘Mr Mullen, when you say Mr Wade kept an eye on your house, what exactly do you mean?’

‘We gave him a spare key. So if we were away for the weekend, he could get in to deal with any emergencies.’

‘Wait a minute – he has a key to your house?’

‘Yes, of course.’

Fry shook her head at the memory of her conversation with Mullen. As far as she was concerned, the question of who’d killed Lindsay Mullen and the two boys in the fire remained open. Despite his parents’ protestations, it would be easy to blame John Lowther and leave it at that. But she was feeling guilty that she’d been so wrong about him. Her preconceptions had overruled her judgement. Bad mistake.

She considered Brian Mullen again. He was one of only two people she could definitely place at the scene around the time of the fire. Mullen had a key to the house, so he wouldn’t have needed to break in through the side window. Of course, the damage to the window might simply have been a blind, to make everyone think there had been a break-in.

She wondered whether she ought to have seized Mullen’s clothes for forensic examination at an early stage in the enquiry. But it would have been a pointless exercise, even immediately after the incident. Mullen had legitimate reasons for his clothes being impregnated with smoke, or even singed by the fire. He’d tried to get into the house to rescue his children, hadn’t he? He had plenty of witnesses to that fact, including the two firefighters who’d physically dragged him back to the pavement. It took a bit of clever forward planning to contaminate forensic evidence like that. She couldn’t believe Brian Mullen had it in him.

But no, she shouldn’t rule out it out completely. No more false assumptions.

Gradually, Fry found her thoughts focusing on Keith Wade. The perfect neighbour, the assiduous member of Neighbourhood Watch. The keen amateur photographer. The only other person she knew to have been at the scene when the fire started.

Fry paused and checked her email. Wade had promised to send her some of his photos, but they hadn’t arrived yet. She doubted if they ever would.

Then another thought struck her. Brian Mullen had an alibi for the time of the fire – he’d been at the Broken Wheel with Jed Skinner until the early hours of the morning. In Wade’s case, it was that very same fact that had made it possible for him to get into the Mullens’ house. If Brian hadn’t been out late that night, the front door of number 32 would have been bolted on the inside. But Lindsay had left the bolts off for her husband to come home. Wade could have known that quite easily, couldn’t he?

There was one person who wasn’t out with the search teams. He wasn’t on duty because he was at home, recovering from his unexpected dip in the trapped waters of the Derwent. Fry dialled his number.

‘Ben,’ she said, ‘can I bounce something off you?’

‘Yes, I’m fine. Thanks for asking, Diane.’

‘Oh. Well, I can tell you’re all right by the way you sound.’

Cooper sighed. ‘What did you want to bounce off me?’

‘Brian Mullen. You know that he denied the arguments with his wife?’

‘Yes.’

‘Whose word do we have that those arguments ever took place?’

Cooper considered the question for a moment. ‘Well, the lady on one side of the Mullens heard the row about the carpet.’

‘Which is the only one Brian admits to. And the rest?’

‘We only have the other neighbour’s word for those.’

‘Keith Wade.’

‘Yes, Wade. Why, Diane?’

‘I’m thinking of getting Mr Wade in. Perhaps he wasn’t such a good friend of the Mullens, after all.’

‘But he seems to have been the perfect next-door neighbour.’

‘Maybe.’

‘Did the prints come back from the can of lighter fluid?’

‘Yes, just today. I’m going to ask Mr Wade to give his prints for comparison.’

‘He’s lived next door to the Mullens for six years,’ said Cooper. ‘And they got on fine, by all accounts. Why would he decide to do them harm? What would have been his motive?’

‘Motive?’

‘Yes, motive. That’s a bit of a problem all round, isn’t it? Juries like a motive. They’re never entirely happy if they don’t get one, you know.’