cat's face coloured quickly. 'god, he makes me so furious. he does it to wreck anything mother does, anything to stop other people having a good time, anything to put a curse on an event.'

'he seems rather bitter.'

'he is.'

'has he had disappointments?'

'no. well - si not going into medicine was a blow. as if there weren't plenty of serrailler doctors to keep him happy. he hated retiring, hated it. he was resentful, depressed, angry ... whereas my mother just accepted the inevitable and got on with the rest of her life.'

'and how.'

'absolutely. dad wallowed in self-pity for a couple of years and then took to being rude. i'm sorry you copped it and i apologise.'

'i've coped with worse - don't think about it. i was more puzzled than anything else.'

their coffees came and cat stirred her espresso several times, before she looked up at freya and said, 'there's martha too, of course. has si mentioned her?'

'no, but ...'

'no, i suppose he wouldn't tell people at work. he finds it difficult.'

'i have seen simon outside work.'

'oh?' cat looked at her sharply.

'we had dinner.'

'right.'

freya wanted desperately to tell cat about the evening in simon's flat, about the dinner at the italian restaurant, about her feelings. the conversation might open into a new realm of intimacy between them. instead, cat said, 'martha is our younger sister ... ten years younger than us. you know we're triplets? there's ivo as well, in australia.'

'yes, simon told me.'

'martha is very seriously handicapped, mentally and physically. she's always been so. the only surprise is that she didn't die as a child. she lives in a special home at chanvy wood. it has eaten my father's life away and he barely mentions her - i don't think he and i have had more than two or three conversations about martha in my life. if anything made him bitter and angry and resentful it was that.'

'hard for meriel.'

'very. but then, a lot of things have been hard for her and she has simply shouldered them and batted on. i may not always get on easily with ma - she drives me nuts sometimes - but i admire her more than i can express.'

'does your father blame anyone - or anything for martha's condition?'

'i've no idea. oh, himself, probably, deep down in a place no one would ever be able to get to. of course it's nonsense, it was simply a chromosomal accident. there's no history of it in either family. but it's hard to be rational about something like this when it happens to you. i know, i've dealt with patients in the same situation.'

'i wonder why simon didn't mention it.'

'simon has a lot of my father in him, but just in a more positive way. he's very private too ... there are places just as deep in him. you just don't go there.'

'no one?'

cat gave her a long look. 'no one. it's none of my business, freya, but ... just don't try. i love my brother dearly but i'm probably the only woman in the world apart from mother who can do so.'

she drained her coffee and reached down to get her carrier bags together. 'i must get off home with my vests and knickers.' she started to get out her purse but freya put out her hand. 'no, these are on the cid. you've been helping the police with their inquiries. actually, you have - i needed to talk over this starly business.'

'come and see us at home, will you? if you could bear the chaos of sunday lunch?'

'i'd love to.'

'i'll ring.' cat bent down suddenly and touched freya's cheek with her own. 'i'm really glad i looked in through the window.'

freya watched her leave, bundling with her bags through the door, and felt elated, in spite of the warning about simon, the same warning that had come from sharon medcalf. she liked cat for herself. she also thought that, in spite of the dutiful speech, cat liked her and might even see her as good for her brother. please, she said, putting her notebook away, yes, please.

forty

he had gone to the unit at half past five that morning in order to look at the real debbie so that he had her clearly in mind, as she was now and as she had been. when he arrived on the perimeter of the hill, they were already there, crowds of them, police vans, reporters, television crews, like a film set with all the hangers-on those entailed. it was early but plenty of people had heard about it and come to stare, women mainly, and a few teenagers before they went on to catch the school buses.

he had been determined to stay away, knowing perfectly well what all the psychologists and the profilers said about people like him. 'they will always return to the scene in some way or other. they can't keep away. if there is a search, they may offer help, if there is a public appeal, they may come forward with spurious information, if there is a reconstruction they will hang about to watch.'

he had no need. what had happened on the hill was unimportant, merely a necessary prelude. what mattered was what he did in the unit. he was not interested in the hunt, the capture, the kill. he understood perfectly why bodysnatchers had been employed in those dark streets of edinburgh centuries ago. if he could have employed people to bring the necessary bodies to him, he would have done so.

what drove him to the hill this morning was the desire to see how the police managed things, what mistakes they made, how far they got it wrong. there could be no outcome of course. however many people came to watch, however many came forward, none of them could be of any use because none of them had been there. no one had been there. he was the only one who knew what had happened.

he hesitated. in the group of uniformed police around one of the vans, he saw the young woman he had met at the dinner party, freya graffham. if she saw him, he would have to speak to her, would have to have a reason for being here. he moved out of her line of sight a little and began to think. but it came to him quite quickly and easily, as things always did. he knew what he was going to say and rather looked forward to saying it. but the scene was set, the actors were waiting, the curtain was about to rise. he went to the left a little along the path, to get a clear view.

he could see at once that they had got it wrong. the girl was not fat enough and her hair was slightly too fair. but the fleece jacket was right, and the dreadful acne. another young woman was talking to her, head close, talking, talking, gesturing with her hands. the flatmate.

someone called for quiet. there was a moment of absolute stillness. then the girl began walking and the cameras started to roll, the television crew walking backwards in front of her, the men with the furry microphones alongside.

the clothes were identical and she walked in almost exactly the same way. almost. he watched. she was crossing the road now, heading for the opening that led to the hill itself. he wanted to shout directions to her, tell her to move faster, tell her to change her expression, and to look up at the hill, not ahead. whoever the girl was, she was too conscious of the camera ahead of her, the walk was too hesitant.

everyone else watched intently, some of them, including freya graffham following in a group some yards behind the girl. freya had not seen him, he was quite certain of that. better that way. his story would be of more use later.

the girl was on the hill now and the others were staying back. the weather was not right but as he watched her, apparently alone, going towards the point at which they had met, he realised that excitement was rising in him. he knew what was going to happen, it was running in his head, reeling out like a film he had already seen and whose ending was perfectly right. for a few seconds, she veered in the wrong direction and he wanted to call out to her, but then she turned again and then everything was right, it was as though she knew, as though she was debbie, not a stand-in, and he felt a surge of power. it was extraordinary. she was doing as he wanted. she was obeying his silent orders, as if she were one of the remote-control planes boys flew on the hill on sunday mornings. every footstep was as he directed. he had to hold himself from running to meet her. she was almost there, poor, fat, badly dressed, spotty girl. how could there be two of them in the world? he had no need of two but if he had been on his own, he would have taken her all the same.

she was a few yards away. he held his breath until his chest was strained. someone shouted. the woman. freya graffham.

'ok, caroline, ok, you can stop there.'

freya came running up and the pack of them followed. everything was ruined, in the last few seconds, the last few strides. the film had broken down.

he watched graffham, her hand on the girl's shoulder. he could no longer hear her. the girl had taken him to the edge and then the policewoman had pulled him back.

he wanted to kill her.

by the time cat deerbon drove round the perimeter road on her way to the surgery, the hill was empty, but she had deliberately taken the detour to try and remember anything at all about debbie parker that might be useful. she had been a funny girl, on the one hand seriously depressed, disfigured by the acne, overweight - and yet when she had come into the surgery, she had not made cat feel drained and tired, as so many of her patients with low moods did. they had joked, debbie had made sharp, observant remarks, there had been a wit and a warmth there, beneath the doleful outer layer. and now, where was she? off with some gypsy-hippie tribe, travelling in an ancient bus and never washing? on the road to the gurus of india? neither seemed likely.

the disappearance of mrs chater was even more troubling. cat thought of the hours she had sat in the hot front room with her and her dying husband. no, she was not a woman to vanish without warning either. she was made of tougher stuff, the type of woman who would soldier on for however many years she had left, and make the best of things. she was a stayer not a runner. cat thought the same was probably true of debbie.

she pulled into the surgery car park and sat for a moment after turning off the engine. in the pit of her stomach, a hollow, slightly painful sensation made her uneasy. dead, she thought. they are both dead. how do i know that? why am i so sure? freya graffham had asked her if there was anything she could tell her about the two women and in one sense there was a great deal - everything she had just been thinking. but what did that amount to, in terms of a police investigation? nothing. vague ominous feelings. they would not be worth ringing in to describe.

but she wanted to talk to freya again. she liked her. she had enjoyed their chance meeting and lunch. and she wished very much that simon did not have a place in the picture. she had recognised the signs given out by freya only too well. there had been enough of them in the past, heaven knew. si attracted women, unsurprisingly. si liked women, enjoyed their company, took them out, talked to them and, even more important, listened to them carefully. after which, he panicked. besides, there was presumably still diana.

cat was the only member of the family, and possibly the only other person at all, who knew about diana mason. simon had known her for five or six years, after they had met in florence, where he had gone, as so often, to draw. they had struck up a conversation, discovered their hotels were in the same street. that might have been that, but for some reason, it was not. when they returned to england, si had telephoned her.

diana mason lived in london and had been widowed over twenty years before and never wanted to remarry. instead, she had wanted to find the career she had never begun, and with the money her husband had left her, she had bought her first small restaurant, in hampstead. now, all those years later, she owned a chain of nine, all called mason, in london, and in smart, cleverly chosen places like bath, winchester, cambridge and brighton. masons were relaxed brasseries with excellent food, open from ten until ten, serving the best coffees, ices and salads in an american style, welcoming to children and families and students, with exactly the right atmosphere, furnishings, staff, drinks. diana had designed and chosen everything, every detail was decided upon by her, and she now took the sensible view that she had found a winning formula and should stick to it. she worked hard at it, constantly driving between her restaurants checking details, talking to staff, eating in each branch in turn. as a result, she had made a lot of money. several larger restaurant chains had offered to buy her out but she had always turned them down, saying that when she was no longer having fun she would quit, but that for now, she was still enjoying herself. the relationship between diana and simon was unorthodox, and it suited them both. cat had long ago decided that they were not in love with one another, and that for this very reason, it worked well. they were fond of one another, enjoyed one another's company, saw one another for a weekend several times a year, once or twice had gone on holiday again. but they were both independent people who, for different reasons, preferred not to have permanent ties. they both liked their work and their own space, their own friends, their own lives.

added to which, diana mason was ten years older.

simon almost never mentioned her, even to cat, who had sometimes wondered how much either of them would mind if the other fell seriously in love with someone else. probably not much.

still, women like freya graffham, nice women, worried her. si was either obtuse or chose not to notice the broken hearts that regularly lay about him. in a way, he was indifferent, even callous, and freya, for one, deserved better. but how to warn her, how to broach the subject at all was a problem cat would shelve for the time being. apart from anything else, she knew from experience that if freya was as in love with her brother as cat suspected, she would be beyond the stage of taking kindly to any warnings whatsoever.

an hour or so later, cat was washing her hands after attending to a child with a suppurating eardrum - why couldn't the mother have so much as given the poor kid a clean pad of paper tissues to hold against it? - when the phone rang.

'can you take a call from aidan sharpe? he says he can call back later if not.'

'no, i'll take it, give me a break.'

'tea?'

'you read my thoughts. thanks.'

the outside line connected in with a click. 'aidan? good morning.'

'cat, my dear, is this a very inopportune time? i did say i would be happy to call back.'

she smiled at his rather old-fashioned way of speaking, his extreme courtesy. chris always said aidan sharpe's manners went with bow ties.

'it's fine. i could do with a break.'

'bad morning?'

'busy. you?'