Sally kept up a commentary into the microphone suspended above the table.

‘There seem to be traces of adhesive on the wrists, face and ankles so it looks like she was restrained with some sort of tape, possibly for some time before she was actually killed. The angle of the knife wounds indicate she was stabbed with a slight downward thrust,’ said Sally without emotion as she penetrated the wound in the dead girl’s chest with a sharp instrument. ‘Which means that her killer was probably taller than her and right handed.’

‘Can’t you be more specific, Sal?’ Emily spoke into the microphone in front of her.

‘I can only tell you what I find. Conjecture costs extra.’

Joe noticed Sally glance in his direction as she picked up the saw that would slice the top off Petulia Ferribie’s skull. The pathologist was an attractive woman with a mischievous sense of humour and sometimes he wondered why he didn’t just ask her out for a meal. But since that CID Christmas party when she’d had too much to drink and made it plain she fancied him, he suspected that her embarrassment had erected a barrier between them. Perhaps he would attempt to break down that barrier one day. But with Pet lying there with her internal organs open to view, it seemed inappropriate to think about it.

‘There’s no sign of sexual assault,’ Sally said. ‘In fact she was a virgin. I didn’t think you got many of them to the pound at Eborby University.’

Joe raised his eyebrows and looked at Emily.

‘That’s a turn up for the books,’ she said. ‘So we’re not looking for a lover or a rapist?’

‘Doesn’t look like it,’ said Sally. ‘Was she robbed?’

‘No handbag was found with her. But her purse was in her pocket, as were her keys. There was a five pound note in her purse and a bit of loose change. And the body was moved,’ Emily said. ‘I’ve yet to come across a mugger who goes to that much trouble. Anything else we should know, Sal?’

‘The toxicology tests will take a while to come back but I’m afraid I can’t add anything to what I’ve already told you.’

Joe saw Emily sigh. The dead girl’s clothes would be sent to the lab where they would be examined for any minute clues to where she was killed. But for the moment they had little to go on.

They left the mortuary and made for the car park.

‘Where to now?’ Joe said as he unlocked the car door.

‘I’m off home,’ said Emily. ‘But I’ll be available if there are any developments.’

Joe drove them back to headquarters and dropped Emily off in the car park before walking up to the incident room.

When he entered the office Sunny greeted him with a raised hand and Joe knew from his expression that he’d found something new.

‘I’ve been doing some digging on the people we’ve interviewed so far and one of them’s done time for murder,’ Sunny said, handing Joe a sheet of paper. ‘I reckon we’ve got ourselves a prime suspect.’

‘He’s got an alibi.’

‘It has been known for people to tell us porkies from time to time.’ Sunny had always had a cynical approach to human nature.

Joe looked at his watch then he studied the details Sunny had given him. ‘We’ll send someone round to pick him up. I’ll give the boss a ring.’

He tried to focus on his work but he couldn’t concentrate because the whispering had begun as it often did once darkness fell. At first he’d thought it was the wind in the trees but now it seemed to come from within the house, like hushed voices in a distant room, talking so quietly that he could never quite make out the words. He sat still and listened, wondering whether he was going mad.

The others claimed that they hadn’t heard it but he knew from the look in their eyes that they had. He was sure that’s why Jason had suggested the seance, so he could find out what they were dealing with. But, of course, Jason had denied it. According to him, he’d sensed nothing strange in the house. The seance had been ‘a laugh’. No more.

But Matt felt that it was time to find out for sure. Caro would disapprove and Jason would mock but he needed to settle the question once and for all.

He opened the top drawer of his battered desk and took out the newspaper cutting. The Reverend George Merryweather’s email address was on it and, after a short period of thought, Matt switched on his computer and began to type.

Then they’d hit the jackpot when they’d discovered that, at the age of sixteen, Pet’s landlord, Andy Cassidy had murdered his own sister and had been committed to a secure hospital for five years. His sister, Grace, had been a year younger than him and a talented pianist. He had stabbed her with a kitchen knife and had hacked off three of her fingers before his horrified mother had discovered him kneeling by her body, sobbing.

According to psychiatric reports he’d been pathologically jealous of his sister for most of his life, envying her musical talent and habitually seeking attention in the most destructive of ways. However, he’d been adamant that he’d done no wrong, claiming that he’d found his sister like that and been too shocked to get help. Nobody had believed him.

After Grace’s death he’d blossomed academically and he’d gained good GCSEs in the secure hospital, something his doctors had taken as a sign of his recovery. On his release he’d gone to college to do his A Levels and had won a place at Eborby University studying psychology of all things. His psychiatrists had pronounced him cured. He’d been one of their success stories.

The files also mentioned that Ian Zepper had been Grace Cassidy’s piano teacher and Joe thought this might explain the animosity Cassidy clearly felt towards him. And if that level of resentment still existed, it might mean that the psychiatrist’s verdict had been over-optimistic.

The fact that Cassidy had murdered his own sister so brutally put him right at the top of their suspect list. It was just a question of breaking his alibi and getting the evidence.

Cassidy’s alibi had been provided by a man called Ethan McNeil, an estate agent he did business with from time to time; a man he described as an old acquaintance. Uniform had called at McNeil’s address in the suburb of Bacombe and his wife had confirmed he’d indeed been out at Cassidy’s and hadn’t got home till after midnight. But he and Emily still planned to pay him a visit at work first thing the next day. They’d have more chance of getting at the truth if they caught him unprepared.

Joe switched on the TV. It was a detective drama that bore scant resemblance to real life but he left it on for that very reason. He needed something to take his mind off the day . . . and off the possibility that Kirsten might contact him any moment with more accusations. He felt unable to relax knowing she was there in Eborby, working against him in the shadows, spreading poison.

He opened a can of beans and put two slices of bread in the toaster. Student food; comfort food. He had just finished eating when the phone rang and he used the remote control to kill the volume of the TV before picking up the receiver. Fearing that it would be Kirsten, he felt his hand shaking a little as he said a wary hello. But when he heard the cheerful voice on the other end of the line, he smiled to himself in sheer relief.

‘I hope I’m not interrupting anything important,’ the voice said.

‘I never mind being interrupted by you, George. How are you?’

‘Remarkably well. I presume you’re dealing with the murder of that poor girl at the leisure centre?’

‘Yes.’

‘Actually . . .’ George paused and Joe knew something important was coming. ‘I’ve just been speaking to one of her housemates. A young man called Matt Bawtry.’

‘I’ve met him.’

‘He’s worried.’

‘And he contacted you rather than the police?’

‘That’s the point, Joe. His worries are rather more my territory than yours. He thinks there’s a malevolent presence in the house.’

Joe remembered how he’d felt when he entered thirteen Torland Place. There had definitely been some indefinable quality about the atmosphere – hostility perhaps – but he’d put it down to the fraught relationship between the occupants. But perhaps it stemmed from something else. Something deeper.

‘I don’t know what Matt told you but the house does have a rather gruesome history. In the nineteenth century a man called Obediah Shrowton butchered his family and a couple of servants there. He’s invited me round tomorrow. I’ll say a few prayers . . . the usual. I don’t suppose you’ll have time to . . .’

‘Probably not, George. Sorry.’ He was about to say they had a suspect to bring in but assuming Cassidy’s guilt at this early stage was probably tempting fate.

‘Matt suspects that the poor girl’s death’s got something to do with the house.’

Joe was about to say: ‘That’s nonsense.’ But he stopped himself. They didn’t have a clue why Pet died. A connection with the house was as likely as anything else. ‘He never mentioned all this to us.’

‘Perhaps he thought you wouldn’t take him seriously. Sometimes people tell me things they wouldn’t say to a policeman,’ said George without any hint of smugness. ‘So if I learn anything – anything that’s not personal or confidential, of course – I’ll let you know.’

‘Thanks, George,’ said Joe before promising that he’d arrange to see him soon. Perhaps George would be the person to talk to about the problem of Kirsten. Or maybe that was something best kept to himself.

He opened a bottle of Old Peculier and settled down in front of the TV.

The pictures of the Torland Place party that Caro had provided were pinned up on the noticeboard. Nobody at the house had been able to identify the person dressed as the Grim Reaper. It was a mystery. One that Emily wanted to solve.

When she had finished speaking, she grabbed hold of Joe’s arm and steered him into her office.

‘You’re on top form today,’ he said.

‘I want this sorted. We need to see Cassidy,’ she hesitated. ‘Her housemates hinted that he was sniffing after Pet. What if she turned him down and he reacted like he did when he killed his sister? It’s the same MO, Joe. Stabbed twice in the heart. It’s too much of a coincidence, don’t you think.’

‘He cut off his sister’s fingers.’

‘Pet’s tongue was cut out. Grace Cassidy’s crime was being a good pianist. He might have punished Pet in a different way. Perhaps she’s given away some secret or said something he didn’t like.’

‘I take it he’s not back home yet?’

‘I’ve got a patrol car waiting outside his house. I don’t want him warned off by that Anna. She looks the devoted type.’

‘So are we going to blow his alibi to bits?’

She looked at her watch. ‘Uniform couldn’t get hold of Ethan McNeil last night but we know where he works and he should be arriving at his office about now. I want to go and spoil his day before he has a chance to tuck into his first cappuccino.’

The office of McNeil and Dutton, Estate Agents, was a short walk away, just the other side of Wendover bridge and opposite the Museum Gardens. And when they arrived the place was locked but they could see a light behind the closed vertical blinds so Emily hammered on the door.

After a minute or so the door opened a few wary inches and when they announced themselves the door swung open to reveal a tall young woman in a short straight navy skirt and matching jacket. She was in her thirties, Joe guessed, with a round face, small eyes and thin lips; the sort Joe’s mother would have described as ‘no oil painting’. And there was a hint of aggression in her manner, like a lioness prepared to defend her young.

‘We’re here to see Mr McNeil,’ said Emily.

The woman drew herself up to her full height. ‘I’ll ask if he can see you . . .’

‘He’ll see us,’ said Emily, taking a step forward. ‘Through there, is he? We’ll find our own way.’

The woman barred the way. ‘I don’t think he’d like . . .’

But Emily marched round her and the woman stood staring at her with barely disguised hostility, angry at this intrusion into her boss’s working day. The picture of the devoted employee.

Emily didn’t bother knocking on Ethan McNeil’s office door. Instead she let herself in, warrant card at the ready. Her intention of getting there before he had his first cappuccino was thwarted – the coffee cup beside a framed photograph of a smiling woman and baby was already half empty and a copy of the Daily Express lay open on his desk.

‘What is it, Carla? I’m busy.’ Then he looked up, his pockmarked face clouded with anger, and when he saw it wasn’t Carla who’d disturbed him he rose from his seat. ‘Who the hell are you?’

Emily made the introductions and McNeil sunk back into his executive leather swivel chair, suddenly meek, the model of cooperation.

‘We’ve been talking to Andrew Cassidy and he says he was with you on Saturday night till midnight.’

‘Er . . . that’s right. I took some papers round for him to have a look at. Why? Andy’s not in any trouble, is he?’

Joe watched the man’s expression. His eyes flickered from side to side as though he were searching for an escape route.

‘Do estate agents usually deal with legal papers?’ said Joe innocently. ‘Isn’t that usually dealt with by solicitors?’

‘They were council reports . . . about planning permission on a property he’s considering buying.’

‘I see. You’re absolutely sure you were with him all night? Was there any time he might have slipped out for half an hour, say? Or perhaps you weren’t sure of the time you left.’

‘I must admit I wasn’t paying much attention to the time but I’m sure I left around midnight.’ He hesitated. ‘Or it could have been a little bit earlier, I suppose – say quarter to. I can’t really be sure.’

‘That’s dedication to the job,’ said Emily. ‘You wouldn’t find me working that late on a Saturday night unless I had no option . . . unless I had something like the death of a young student to investigate.’

McNeil gave her a smooth smile. ‘It’s different when it’s your own company, Chief Inspector. You work whenever you have to and it was the only time Andy could fit the meeting in. He’s a busy man.’

Joe looked at Emily. He could tell that, like him, she didn’t much like the man but that didn’t necessarily mean he was lying.

‘Did you know Petulia Ferribie? She was one of Mr Cassidy’s tenants at thirteen Torland Place.’

‘No.’

‘Do you and Andy Cassidy see much of each other?’ Joe thought the question was worth asking.

‘We have a drink from time to time. Mainly business.’

‘How long have you known him?’

‘Quite a few years actually.’ Joe sensed that the subject was uncomfortable and he thought he knew the reason why.

‘So you know about the time he spent in prison?’

McNeil looked away. ‘Andy was ill. What he did was terrible but they put him in hospital, not prison.’

‘Did you know his sister, Grace?’

It was a few seconds before McNeil answered. ‘I’d met her but I didn’t know her well.’

‘I’m surprised you wanted to keep in touch with him.’

‘I didn’t particularly. But our paths crossed through work and . . . I wouldn’t describe our relationship as close.’ McNeil hesitated. ‘Andy and I don’t share the same interests, Inspector.’

‘Go on.’ Joe caught Emily’s eye. He wanted McNeil to talk, to tell him everything he knew about Cassidy.

‘Sometimes Andy makes me feel a little uncomfortable. His attitude to women and . . .’ He shook his head. ‘Like I said, I don’t want to get him into trouble.’

‘Please. We need to know everything.’

‘It’s just that he’s a bit of a ladies’ man – likes to go out to bars and clubs and parties. I’m happily married with a lovely baby daughter and . . . Well, I’m just not into that sort of thing any more.’

‘What sort of thing?’ Joe looked at Emily who was listening intently.

‘Well, a couple of months ago he asked if I’d like to go to a strip club with him and a few friends. I made an excuse.’

‘What about his girlfriend? Anna, is it?’

‘I think she’s just one in a long line.’

‘Do you know the names of any of his other women?’

McNeil shrugged apologetically. ‘Sorry. Like I said, I’m happily married and I don’t take much interest in what he gets up to.’

‘We’ll send someone along to take a statement,’ she said. ‘And I’d be grateful if you had another think about the time you left Cassidy’s on Saturday night. Perhaps you heard the news on the car radio or . . .’

‘I’m pretty sure it was around midnight but . . .’ Somehow he didn’t sound very convincing.

As they took their leave, Joe gave a reassuring nod to the woman who had now resumed her place at the front desk.

‘I think it’s time we found out more about Mr Andrew Cassidy,’ said Emily, shutting the office door behind her and stepping out on to the street.