There was the tang of manure in the air and the smell of the musty grass and the cow parsley got inside Joanna's nose and made her sneeze.

'Bad luck,' her mother said, 'you're the one that got my allergies.' Their mother's dark hair and pale skin went to her 'beautiful boy' Joseph, her green eyes and her 'painter's hands' went to Jessica. Joanna got the allergies. Bad luck. Joseph and their mother shared a birthday too although Joseph hadn't had any birthdays yet. In another week it would be his first. 'That's a special birthday,' their mother said. Joanna thought all birthdays were special.

Their mother was wearing Joanna's favourite dress, blue with a pattern of red strawberries. Their mother said it was old and next summer she would cut it up and make something for Joanna out of it if she liked. Joanna could see the muscles on her mother's tanned legs moving as she pushed the buggy up the hill. She was strong. Their father said she was 'fierce'. Joanna liked that word. Jessica was fierce too. Joseph was nothing yet. He was just a baby, fat and happy. He liked oatmeal and mashed banana, and the mobile of little paper birds their mother had made for him that hung above his cot. He liked being tickled by his sisters. He liked his sisters.

Joanna could feel sweat running down her back. Her worn cotton dress was sticking to her skin. The dress was a hand-me-down from Jessica. 'Poor but honest,' their mother laughed. Her big mouth turned down when she laughed so that she never seemed happy even when she was. Everything Joanna had was handed down from Jessica. It was as if without Jessica there would be no Joanna. Joanna filled the spaces Jessica left behind as she moved on.

Invisible on the other side of the hedge, a cow made a bellowing noise that made her jump. 'It's just a cow,' her mother said.

'Red Devons,' Jessica said, even though she couldn't see them. How did she know? She knew the names of everything, seen and unseen. Joanna wondered if she would ever know all the things that Jessica knew.

After you had walked along the lane for a while you came to a wooden gate with a stile. They couldn't get the buggy through the stile so they had to open the gate. Jessica let the dog off the lead and he scrambled up and over the gate in the way that Jessica had taught him. The sign on the gate said 'Please Close The Gate Behind You'. Jessica always ran ahead and undid the clasp and then they both pushed at the gate and swung on it as it opened. Their mother had to heave and shove at the buggy because all the winter mud had dried into deep awkward ruts that the wheels got stuck in. They swung on the gate to close it as well. Jessica checked the clasp. Sometimes they hung upside down on the gate and their hair reached the ground like brooms sweeping the dust and their mother said, 'Don't do that.'

The track bordered a field. 'Wheat,' Jessica said. The wheat was very high although not as high as the hedges in the lane. 'They'll be harvesting soon,' their mother said. 'Cutting it down,' she added, for Joanna's benefit. 'Then we'll sneeze and wheeze, the pair of us. 'Joanna was already wheezing, she could hear the breath whistling in her chest.

The dog ran into the field and disappeared. A moment later he sprang out of the wheat again. Last week Joanna had followed the dog into the field and got lost and no one could find her for a long time. She could hear them calling her, moving further and further away. Nobody heard her when she called back. The dog found her.

They stopped half Way along and sat down on the grass at the side of the track, under the shady trees. Their mother took the plastic carrier bags off the buggy handles and from one of the bags brought out some little cartons of orange juice and a box of chocolate finger biscuits. The orange juice was warm and the chocolate biscuits had melted together. They gave some of the biscuits to the dog. Their mother laughed with her down-turned mouth and said, 'God, what a mess,' and looked in the baby-bag and found wipes for their chocolate-covered hands and mouths. When they lived in London they used to have proper picnics, loading up the boot of the car with a big wicker basket that had belonged to their mother's mother who was rich but dead (which was just as well apparently because it meant she didn't have to see her only daughter married to a selfish, fornicating waster). If their grandmother was rich why didn't they have any money? 'I eloped,' their mother said. 'I ran away to marry your father. It was very romantic. At the time. We had nothing.'

'You had the picnic basket,' Jessica said and their mother laughed and said, 'You can be very funny, you know,' and Jessica said, 'I do know.'

Joseph woke up and their mother undid the front of her strawberry-covered dress and fed him. He fell asleep again while he was sucking. 'Poor lamb,' their mother said. 'He can't shake off this cold.' She put him back in the buggy and said, 'Right. Let's get home, we can get out the garden hose and you can cool off.'

He seemed to come out of nowhere. They noticed him because the dog growled, making an odd, bubbling noise in his throat that Joanna had never heard before.

He walked very fast towards them, growing bigger all the time. He was making a funny huffing, puffing noise. You expected him to walk past and say 'Nice afternoon,' or 'Hello,' because people always said that ifyou passed them in the lane or on the track, but he didn't say anything. Their mother would usually say, 'Lovely day,' or, 'It's certainly hot, isn't it?' when she passed people but she didn't say anything to this man. Instead she set off walking fast, pushing hard on the buggy. She left the plastic bags of shopping on the grass and Joanna was going to pick one up but their mother said, 'Leave it.' There was something in her voice, something in her face, that frightened Joanna. Jessica grabbed her by the hand and said, 'Hurry up, Joanna,' sharply, like a grown-up. Joanna was reminded of the time their mother threw the blue-and-white-striped jug at their father.

Now the man was walking in the same direction as they were, on the other side of their mother. Their mother was moving very fast, saying, 'Come on, quickly, keep up,' to them. She sounded breathless. Then the dog ran in front of the man and started barking and jumping up as if it was trying to block the man's path. Without any warning he kicked the dog so hard that it sailed into the air and landed in the wheat. They couldn't see it but they could hear the terrible squealing noise that it was making. Jessica stood in front of the man and screamed something at him, jabbing her finger at him and taking great gulps of air as if she couldn't breathe and then she ran into the field after the dog. Everything was bad. There was no question about it.

Joanna was staring at the wheat, trying to see where Jessica and the dog had gone and it took a moment for her to notice that her mother was fighting the man, punching him with her fists. But the man had a knife and he kept raising it in the air so that it shone like silver in the hot afternoon sun. Her mother started to scream. There was blood on her face, on her hands, on her strong legs, on her strawberry dress. Then Joanna realized that her mother wasn't screaming at the man, she was screaming at her.

Their mother was cut down where she stood, the great silver knife carving through her heart as if it was slicing butcher's meat. She was thirty-six years old.

He must have stabbed Jessica too before she ran off because there was a trail of blood, a path that led them to her, although not at first because the field of wheat had closed around her, like a golden blanket. She was lying with her arms around the body of the dog and their blood had mingled and soaked into the dry earth, feeding the grain, like a sacrifice to the harvest. Joseph died where he was, strapped into the pushchair. Joanna liked to think that he never woke up but she didn't know.