I remembered what that woman said as I lay shivering under my duvet. He'll never trouble you again. Well, she was wrong because he was troubling me now. Suddenly, I understood something else: the man who talked to Theo and Ben in the park. He knew all our names. He had dark hair and round glasses like Harry Potter.

Dad was stalking us.

In films and books, the murderer is the last person you expect it to be. Normally it's the motherly cook or the shy young vicar. It's never the creepy guy with the weird laugh who's always sharpening knives. It was like that with Mum being killed. Until then, I used to think my dad was the best. He was a fun person who wore cuddly jerseys, took us to feed the ducks and read bedtime stories. He looked after us. He kept us safe. I thought I was very lucky, because in my eyes my dad was much more handsome and kind than other people's.

The kitchen door creaked. Gramps' voice. 'Scarlet! Please come down. Sca-ar-letta!'

I crept along to the bathroom, locked the door and faced myself in the mirror. I didn't look too good. I had little piggy eyes from crying, so I filled a basin with warm water and splashed it over my face. That helped. I ran a comb through my fringe, exhaled loudly-I learned that in drama, it's good for managing nerves-and forced myself down the stairs and into the kitchen.

Gramps had his arm around Hannah, and she was leaning her face against his shoulder. They weren't speaking, and there was a terrible sadness hanging about them. It made me feel dark. He kissed the top of her head.

'We have to play this absolutely straight,' he murmured into her hair.

'Play what absolutely straight?' I asked.

Hannah Freddie was playing his harpsichord as I stepped into the hall that Monday morning. Complex cadences permeated the air with calm, like a lavender candle.

'Hello, Freddie?' I called, stopping by the mirror to pat my hair. More grey than fair now, but the hairdresser did wonders and it was cut in quite a youthful bob. I liked the way it swung.

Mondays were oases in the pandemonium of our lives. Ben went to nursery school, and I had only one lecture. Freddie and I had developed a small, contented ritual: I always visited the delicatessen on Micklegate and came home with French bread, brie and a salad. We'd have lunch at the kitchen table. This was how I used to imagine our autumn years would be: just the two of us, talking and reading and loving our way into a mellow old age, visited by our grandchildren at the weekends and spoiling them rotten. We'd begun saving for a cruise to Alaska and an adventure on the Trans-Siberian railway. I never in my wildest nightmares imagined we might become our grandchildren's only guardians, agonising over every decision, our lives entirely subsumed by their needs. So I looked forward to Monday lunchtimes.

I was warming my hands on the Aga when the music stopped. Frederick appeared in the doorway. He lit up at the sight of me-literally, as though a torch had switched on behind the fading honey-brown of his eyes. I felt my own face lift in response.

'Hello!' he cried, with the emphasis on the second syllable. Hel-lo! He always managed to make it sound as though my arrival was a delightful surprise. He came over to kiss me. 'I didn't hear you. How were your undergrads?'

'Two were actually asleep, one played games on his phone, and one was grinning at her laptop-I'm fairly sure she was watching cute cat videos on YouTube.'

Frederick had opened the fridge door and was peering at the shelves. 'I'm not sure what we're having for lunch.'

I felt a twinge of irritation at his scattiness. He knew perfectly well what we were having! I'd bought brie and baguettes and other goodies, as I had done every Monday for years. It was waiting on the table. I could smell warm crust, faintly yeasty.

'It's all here,' I said briskly, taking a seat. 'You ready to eat?'

No, he wasn't ready. He stooped over a chair back, gripping it. There were age spots on his knuckles. 'A letter came this morning.'

I sat with a baguette in my hand and a rictus smile on my face, looking up at him. For some reason, I was thinking of the moment we heard Zoe had been murdered. We were sitting at that same table; we were happy, laughing, hosting a dinner party for good friends.

It was murder, you know. The lawyers did a little pleasant plea-bargaining over a cup of coffee (they denied it, but I'm sure that's what happened) tipped sweet-smelling scent all over the crime and rechristened it manslaughter. But I know what it was, all right, and so did the judge and the police and the ushers and the woman from the CPS and all those wigged barristers who wouldn't meet my eye.

Frederick pushed an envelope across the table. 'He wants to see them.'

'They don't want to see him.'

'He warned us he'd go to court.'

I read through the papers with a sense of disbelief. It was an application on a standard form. It sounded innocuous enough: Joseph William Scott applies for contact with the children Scarlet Zoe Scott, Theodore Marcus Scott and Benjamin Frederick Scott.

'Will we never have peace?' I whispered.

'I don't think so.'

'If anyone else had killed our daughter right in front of her own children, we'd never have to see him again! Yet this monster can walk into a court and ask-no, not ask, demand-that we offer them up like sacrificial lambs!' I took a long breath. 'It's not happening, Frederick. Last time they clapped eyes on that man . . .'

I didn't need to finish the sentence. We both knew what had happened the last time the children saw Joseph Scott. That was the moment when the world came to an end.

Freddie looked weary. 'I think we'd better phone Jane.'

'I'll do it.' As I picked up the phone to call our solicitor, Freddie wandered to a shelf beside the Aga upon which we'd arranged photographs of Zoe. This was instigated by Nanette, a bereavement specialist we brought in to help us in those early days. According to her, in some families there was an unhealthy conspiracy of silence and the dead person was never mentioned; others went to the opposite extreme and made the entire house a sort of shrine, with memorabilia everywhere so that the past was revered more than the present. Instead, Nanette suggested the photo shelf.

'It's to acknowledge Zoe,' she said. 'They need to make new relationships rather than fixating on loss; but let her be a part of family chat around the table, if you can. Share your memories. Don't let her become a taboo subject.' Our kitchen was the hub of our world, so that's where we put most of the pictures.

Frederick put on the glasses he wore on a chain around his neck and picked up a framed photograph. Zoe, thirty-three years old, cross-legged on the bonnet of her beloved old MG. She was wearing jeans and a tiny scrap of a T-shirt, head poised on a dancer's neck. You wouldn't believe she'd given birth to three children. She was so slim. Thin, actually. I used to fuss about it. Her eyes dominated the picture-those luminous eyes that turned heads in the street. You could almost hear her laughter.

Scarlet was pressing her own soft cheek to her mother's, while Theo had squashed himself half onto Zoe's lap. He'd just had an appalling haircut, a black pudding basin, and was scowling at baby Ben, who'd taken prime position in his mother's arms. Midsummer light glanced off their faces, dappled through the umbrella of the lime tree in their garden. The photograph was taken by Freddie, just days before she died. That was the last time we saw Zoe. She seemed so happy.

Too happy. We knew that.

Frederick stood looking down at the picture of his daughter. I saw him touch his forefinger to his mouth, and to her smiling face. He stood for a moment, head bowed. Then he quietly returned the photograph to its place.

By four o'clock my grandsons were home and lolling in various states of scruffiness on beanbags in the sitting room, watching television. I checked that the front door was locked. With Scott prowling around, it was best to be on the safe side. Scarlet had a violin lesson after school on Mondays. She'd be walking home with a very sensible sixth former, so I had no concerns there. I'd begun making a fish pie when I heard her key in the lock.

Freddie heard it too. He put down his Guardian with an expectant smile. 'Aha. Miss Scarlet.'

''Lo?' That was Scarlet's voice.

'Greetings, Scarletta!' called Freddie.

The front door shut with a bang. Scarlet had always done that, ever since her mother died. Always, always. She never shut the door until she was sure there was somebody in the house. Perhaps she didn't trust people to be alive. I heard the violin being dumped by the harpsichord in the bay window and waited for my granddaughter to come and share her day with us, warming her shapely hands on the Aga and complaining that the violin teacher was a witch. I could tell she really wanted to say bitch.

This time, she didn't appear in the kitchen. I heard light footsteps running up the stairs. Freddie levered himself up and stepped out into the hall. 'Hey! Aren't you coming to say hello?'

Her voice sounded faint, as though she had a sore throat. 'In a minute. Just got to do some homework.'

'There's chocolate biscuits.'

'In a minute, Gramps!' Her door slammed shut, and I flinched. Her bedroom used to be Zoe's. I knew exactly how that door sounded when it was slammed.

Freddie reappeared, shrugging. 'Busy, busy,' he muttered unhappily. 'Can I help with anything?'

'You could stir the white sauce. Tedious job.'

He took the wooden spoon out of my hand, stirring distractedly and much too fast.

I touched his arm. 'Stop, Freddie. Stop fretting.'

'She slammed her door.'

'I know.'

He stirred faster still. Sauce slopped out, sizzling and smoking on the hot plate.

'She isn't Zoe,' I said desperately.

'I dread it.' He turned around and leaned against the Aga rail.

'It was at this age, wasn't it, that it first showed itself?'

Signs. Signs ignored, written off as adolescent hormones. Screams. Mugs smashed, doors slammed. Soft young arms pocked with crescent nail-scissor cuts. An adored face pinched with fury as she swept her arm along the sitting-room mantelpiece, hurling china and vases and an antique clock to the floor.

'No,' I said firmly, as I began to lay the table. 'Scarlet's her own woman. She has many of her mother's qualities-talent, for example; brains, looks, a sense of humour and a strong character-but none to be feared.'

Freddie wandered away, shaking his head. He'd completely forgotten about the white sauce. I caught it just as it was rising up the saucepan. He was back in the doorway, calling her.

'Scarlet! Please come down. Sca-ar-letta!'

'Freddie,' I hissed. 'Should we tell her about this?' I jerked my head at the court papers, jammed haphazardly into their envelope.

'No.' He hid them away in a drawer. 'Scare her half to death.'

'I agree, but if we don't warn them, it might come as a ghastly shock.'

He stood with his hands straight down by his sides, swaying a little like a tired soldier. Freddie seemed to need more time to gather his thoughts as he'd grown older, but his words were worth waiting for. They were never empty.

'I think it would be best to wait until after we've discussed it with Jane,' he decided. 'Taken some legal advice. There's no point in upsetting the children unnecessarily. Scott may give up.

He may move away.'

'He may get run over by a bus,' I suggested hopefully.

'Or perhaps we could pay someone to send him for a swim in the Ouse.'

'Hannah!' Tut-tutting gently, Freddie dropped his arm around my shoulder. 'We have to play this absolutely straight.'

'Play what absolutely straight?' asked Scarlet. She was standing in the doorway, green eyes burning in a bloodless face, glaring at us.

Scarlet The pair of them jumped like I'd caught them snogging. Hannah ducked out from under Gramps' arm. She was looking pretty shifty.

'How was violin?' she asked, pretending to be jolly.

'Cancelled.'

'Did you get your homework done?'

'I've still got more to do.'

'How about a cuddle for your old ancestor?' pleaded Gramps. 'I haven't seen you all this livelong day.'

He enveloped me in a bear hug, but I wasn't going to be distracted so easily. 'Play what absolutely straight? I'll keep asking until you spill the beans.'

They looked at one another.

'I'll keep asking,' I warned them.

'Biscuit?' suggested Hannah. There was a burst of activity as they fussed around, force-feeding me lemon squash and Hobnobs. When they shut the kitchen door and both stood awkwardly by the table, I knew for sure that something was going on.

Hannah spoke first. 'Your father is out of prison.'

I know, I thought. I've just seen him. I didn't tell them, though. I knew they'd be absolutely terrified. Anyway, my dad was never mentioned in our family. I'd sooner say a really bad swear word in front of my grandparents-even the 'f' word, even the 'c' word-than my dad's name.

'He wants to see you,' said Hannah. She pulled something out of a drawer. 'He's made this application to the court.'

I stared. 'No! No way.'

'We thought so too. And that's exactly what we're going to tell Jane Whistler.'

Gramps was standing behind my chair. I could feel his fingers spiking up my hair. 'But it's your choice, Scarletta. If you choose to see him, we'll respect your wish.'

Hannah looked as though he'd stuck a fork into her backside. I mean, my father is just like the devil in our house. Gramps might as well have said, 'Go on, smoke a cigarette,' or, 'Hey, why don't you nip out and shoot up heroin and maybe sleep with some random guy in the street?'

I didn't stop to think. I didn't want to think. I ran around the table and grabbed that envelope out of Hannah's hand. I ripped it in half, then quarters-which wasn't easy, because there were a few sheets in there. 'Here's what I think of his application,' I yelled, tossing the bits all over the floor. Then I stamped on them. 'And here's what I think of him!'

'Shh,' said Gramps, looking upset. 'Calm down. You'll make yourself ill, flying into such a rage.'

That just made me even wilder. I wanted to shake him, but even thinking such a horrible thought made me feel guilty. One of the most annoying things about being brought up by grandparents is their old-fashioned ideas. Sometimes it feels like living in the Dark Ages. For instance, the idea that you can make yourself ill just by getting angry. The idea that you can catch a chill from having wet hair. And the idea that eating the disgusting cold jelly off a roast chicken is 'excellent for invalids'. I love Gramps and Hannah but they drive me up the wall sometimes.

Hannah began picking up the pieces from the floor. Her mouth was as straight as a ruler. 'Don't you worry,' she said. 'We'll see him off. Don't tell the boys, will you, Scarlet? There's absolutely no need to be frightening them. This may come to nothing.'

All through dinner the three of us tried to behave as though everything was normal. Theo had some good news about becoming class prefect at school. Ben was being a little twerp, winding Theo up by calling him Ferret Face.

'C'mon, Ben-you too, Theo,' said Gramps, after we'd eaten. 'The girls have homework to do. Let's us lads do the washing-up, then get yourselves ready for bed and I'll tell you a story. What shall it be about?'

The bribe worked. He soon had Theo and Ben lined up with tea towels, and I laid out my homework on the kitchen table while Hannah disappeared off to her computer. Gramps' stories are legendary in our family. You can give him any subject, anything at all.

'A great big, um . . . a big hairy caveman,' suggested Ben.

'A spoon,' said Theo, who was drying one.

'A wee!' screeched Ben, sniggering with his hand over his mouth. He thinks anything to do with toilets is hilarious.

'Hmm . . .' Gramps thought for a while, swishing the water around with his yellow rubber gloves. 'Yes, well, I think this evening we'll hear the story of three Neanderthal children, and how they invented the very first spoon. Of course, wee is an important part of the plot.'

'What are they called?' asked Theo.