Spring is a powerful spell.

The blue. The clouds high up and puffy. The air is warmer than it's been for weeks. "The light was different this morning," I tell Christina. "It woke me up."

She shifts her weight in the deck chair. "Lucky you. Leg cramp woke me up."

We're sitting under the apple tree. Christina brought a blanket from the sofa and wrapped herself up in it, but I'm not cold at all. It's one of those mellow days in March that feel as if the earth is tipping forwards. Daisies sprinkle the lawn. Clusters of tulips sprout at the edges of the fence. The garden even smells different – moist and secretive.

"You all right?" Christina says. "You look a bit weird."

"I'm concentrating."

"On what?"

"Signs."

She groans softly, picks up the holiday brochure from my lap and flicks through the pages. "I'll just torture myself with this then. Tell me when you're done."

I'll never be done.

That rip in the clouds where the light falls through. That brazen bird flying in a straight line right across the sky. There are signs everywhere. Keeping me safe.

Caleb's got into it too now, although in a more practical way. He calls them 'keep-death-away spells'.

He's put garlic above all the doors and at the four corners of my bed. He's made KEEP OUT boards for the front and back gates. He knows it won't work but something in his gestures make me feel safer.

Last night, when we were watching TV, he tied our legs together with a skipping rope. We looked as if we were entering a three-legged race. He said, "No one will take you if you're tied to me."

"They might take you as well!"

He shrugged as if that didn't matter to him. "They won't get you in Sicily either; they won't know where you are."

Tomorrow we fly. A whole week in the sun.

I tease Christina with the brochure, run my finger over the volcanic beach with black sand, the sea edged by mountains, the cafes and piazzas. In some of the photos, Mount Etna squats massively in the background, remote and fiery.

"The volcano's active," I tell her. "It sparks at night, and when it rains, everything gets covered in ash."

"It's not going to rain though, is it? It must be really hot there" She slaps the brochure shut.

"I can't believe your mum bought a ticket for Tobias"

"My dad can't believe it either."

Christina thinks about this for a moment. "I feel sad now."

"It's the hormones."

"Sadder then you'd ever believe."

"Yeah, it's the hormones."

She gazes hopelessly at the sky, then almost immediately turns back to me with a smile on her face. "Did I tell you I'm picking the keys up in three weeks?"

Talking about the apartment always cheers her up. She'll be able to paint and wallpaper, she tells me. She gets quite animated describing the mural she plans for her bedroom, the tropical fish tiles she wants in the bathroom.

It's strange, but as she talks, her body begins to waver at the edges. I try and concentrate on her plans for the kitchen, but it's as if she's caught in a heat haze.

"Are you OK?" she says. "You've got that weird look on your face again."

I sit forward and massage my scalp. I focus on the pain behind my eyes and try and make it go away.

"Shall I get your dad?"

"No."

"A glass of water?"

"No. Stay there. I'll be back in a minute."

"Where are you going?"

I can't see Tobias, but I can hear him. He's turning over the soil so his mum can plant flowers while we're away. I can hear the push of his boot on the spade, the wet resistance of the earth. I go through the gap in the fence. There's the whisper of growing things – buds opening, delicate fronds of green pushing their way into the air.

He's got his jumper off, is only wearing a vest top and jeans. He had his hair cut yesterday and the arc of his neck as it joins his shoulder is shockingly beautiful. He grins when he sees me watching, puts the spade down and walks over.

"Hey, you!"

I lean into him and wait to feel better. He's warm. His skin is salty and smells of baked sunlight.

"I love you." Silence. Startling. Did I mean to say that?

He smiles his tilted smile. "I love you too, Tris"

I put my hand over his mouth. "Don't say it if you don't mean it."

"I do mean it." His breath makes my fingers humid. He kisses my palm.

I bury these things in my heart – the feel of him under my fingers, the taste of him on my mouth. I'll need them, like talismans, to survive an impossible journey.

He brushes my cheek with one finger, from my temple to my chin and then across my lips. "You OK?"

I nod.

He looks down at me, gently puzzled. "You seem quiet. Shall I come and find you when I'm done? We could go out on the bike if you like, say goodbye to the hill for a week."

I nod again. Yes.

He kisses me goodbye. He tastes of butter.

I hold onto the fence as I go back through the gap. A bird is singing a complicated song and Dad's standing on the back step holding a pineapple. These are good signs. There's no need to be afraid.

I go back to my chair. Christina is pretending to be asleep, but she opens one eye as I sit down. "I wonder if you'd fancy him if you weren't sick. I bet he gets on your nerves sometimes. I bet he talks utter crap or wants to have sex with you when you don't feel like it."

"He doesn't."

She scowls at me. "He's a boy, isn't he?"

How can I explain it to her? The comfort of his arm around my shoulder at night? The way his breathing changes with the hours so that I know when it's dawn? Every morning when he wakes up, he kisses me. His hand on my breast keeps my heart beating.

Dad comes up the path, still clutching his pineapple. "You need to come in now. Tori is here."

But I don't want to be inside. I'm having trouble with walls. I want to stay under the apple tree, out in the spring air.

"Ask her to come out, Dad." He shrugs, turns back to the house.

"I need to have a blood test," I tell Christina.

She wrinkles her nose. "All right. It's freezing out here anyway."

Tori squeezes her fingers into sterile gloves. "Love still working its magic then?"

"It's our tenth anniversary tomorrow."

"Ten weeks? Well, it's doing wonders for you. I'm going to start recommending all my patients fall in love."

She holds my arm up to the sky and cleans around the portacath with swabs of gauze. "You packed yet?"

"A couple of dresses. Bikini and sandals."

"That all?"

"What else will I need?"

"Sun cream, sun hat and a sensible cardigan for a start! I don't want to be treating you for sunburn when you get back."

I like her fussing over me. She's been my regular nurse for weeks now. I think I might be her favourite patient.

"How's Bud?"

She smiles wearily. "He's had a cold all week. Although of course, he says it's flu. You know what men are like." I don't really, but I nod anyway. I wonder if her husband loves her if he makes her feel gorgeous if he lies entranced in her arms.

"Why don't you have any children, Tori?"

She looks right at me as she draws blood into the syringe. "I couldn't manage that kind of fear."

She draws a second syringe of blood and transfers it to a bottle, flushes my port with saline and heparin, then packs her things away into her medical bag and stands up. For a moment I think she's going to reach down and hug me, but she doesn't.

"Have a lovely time," she says. "And don't forget to send me a postcard."

I watch her waddle up the path. She turns on the step to wave.

Christina comes back out. "What's she looking for in your blood exactly"

"Disease."

She nods sagely as she sits back down. "Your dad's making lunch by the way. He's going to bring it out in a minute."

A leaf dances. A shadow travels the length of the lawn. There are signs everywhere. Some you make. Some come to you.

Christina grabs my hand and presses it to her belly. "She's moving! Put your hand here – no, here. That's it. Feel it?"

It's a slow roll as if her baby's spinning the laziest of somersaults. I don't want to take my hand away. I want the baby to do it again.

"You're the first person ever to feel that. You did feel it, didn't you?"

"I felt it."

"Imagine her," Christina says. "Really imagine her."

I often do. I've drawn her on the wall above my bed. It's not a great drawing, but all the measurements are accurate – femur, abdomen, head circumference. Number ten on my list. Ellie Beatrice Walker.

"The structures of the spine are in place," I tell Christina. "Thirty-three rings, one hundred and fifty joints and one thousand ligaments. The eyelids are open, did you know that? And the retinas are formed."

Christina blinks at me as if she can't quite believe anyone would know this information. I decide not to tell her that her own heart is working twice as fast, as usual, circulating six litres of blood every minute. I think it would freak her out.

Dad walks up the path. "Here you go, girls." He puts the tray down on the grass between us. Avocado and watercress salad. Pineapple and kiwi slices. A bowl of grapes.

Christina says, "No chance of a burger then?"

He frowns at her, realises she's joking and grins. "I'm going to get the lawnmower out." He goes off to the shed.

Tobias and his mum appear at the gap in the fence. "Lovely day, isn't it?' Evelyn calls.

"It's spring," Christina says, her mouth sprouting watercress.

"Not until the clocks change."

"Must be pollution then."

Evelyn looks alarmed. "A man on the radio said if we stop using cars we could buy the human race another thousand years on the planet."

Tobias laughs, jangles the car keys at her. "Shall we walk to the garden centre then, Mum?"

"No, I want to buy bedding plants. We'd never be able to carry them."

He shakes his head. "We'll be back in an hour."

We watch them walk down the path. At the gate, he gives me a wink.

Christina says, "Now that would definitely annoy me."

I ignore her. I eat a slice of kiwi. It tastes of somewhere else. The sky skitters with clouds, like spring lambs in a strange blue field. The sun comes and goes. Everything feels volatile. Dad hauls the lawnmower from the shed. It's covered in old towels as if it's been hibernating. He used to look after the garden religiously, used to plant and prune, tie things back with bits of string and keep some general order. It's a wilderness now though – the grass bedraggled, the roses nudging their way into the shed.

We laugh at him when the lawnmower won't start, but he doesn't seem to mind, just shrugs at us as if he didn't want to mow the lawn anyway. He goes back into the shed, comes out with some shears and starts cutting back brambles from the fence.

Christina says, "There's this pregnant teens group, did I tell you? They give you cake and tea and show you how to change nappies and stuff. I thought it'd be rubbish, but we had a great laugh."

A plane crosses the sky, leaving a smoky trail. Another plane crosses the first one, making a kiss. Neither plane falls. Christina says, "Are you listening? Because you don't look as if you are."

I rub my eyes, try to focus. She says she's made friends with a girl... something about their due dates being the same... something else about a midwife. She sounds as if she's speaking to me down a tunnel.

I notice how a button strains in the middle of her shirt.

A butterfly lands on the path and spreads its wings. Sunbathing. It's very early in the year for butterflies.

"You sure you're listening?"

Caleb comes through the gate. He dumps his bike on the lawn and runs around the garden twice. "Holidays start here!" he yells. He climbs the apple tree to celebrate, jamming his knees between two branches and squatting there like an elf.

He gets a text, the blue light on his phone flashing amongst the new leaves. It reminds me of a dream I had a few nights ago. In the dream, a blue light shone from my throat every time I opened my mouth.

He sends a text back, quickly receives one in return. He laughs. Another text arrives, then another, like a flock of birds landing in the tree.

"What are you staring at?" He sticks his tongue out at me, jumps out of the tree and runs into the house.

The garden's sunk into shadow. The air feels damp. A sweet wrapper blows down the path. Christina shivers. "I think I might go." She holds me tight as if one of us might fall. "You're very hot. Are you supposed to be?"

Dad sees her out.

Tobias comes through the gap in the fence. "All done." He pulls the deck chair closer to me and sits down. "She bought half the garden centre. It cost a fortune, but she was really into it. She wants to start a herb garden."

Keep-death-away spells. Hold your boyfriend's hand very tight.

"You all right?"

I rest my head on his shoulder. I feel as if I'm waiting for something. There are sounds – the vague chink of dishes from the kitchen, the rustle of leaves, the roar of a faraway engine. The sun has turned to liquid, melting coldly into the horizon.

"You feel very hot." He presses his hand against my forehead, brushes my cheek, feels the back of my neck. "Don't move." He leaves me, runs up the path towards the house.

The planet spins, the wind sifts the trees.

I'm not afraid.

Keep breathing, just keep doing it. It's easy – in and out.

Strange how the ground comes up to meet me, but it feels better to be low. I think about my name while I lie here. Beatrice Prior. A good name. Every seven years our bodies change, every cell. Every seven years we disappear.

"Christ! She's burning up!" Dad's face glimmers right above me. "Call an ambulance!" His voice comes from far away. I want to smile. I want to thank him for being here, but for some reason, I don't seem able to get the words together.

"Don't close your eyes, Beatrice. Can you hear me? Stay with us!"

When I nod, the sky whirls with sickening speed, like falling from a building.

Thank you for reading!