"We think Natasha was trying to get home. It's likely she didn't know her parents had divorced and moved house."

Mr. Hadley's face bends like a white rubber mask. "Oh, Christ. So Piper might have been with her. They both could have escaped."

"It's too early to say."

"You must have some leads."

"We are questioning someone."

"Who?"

"A man who was in the area when Natasha was found."

"What's his name?"

"I'm afraid I can't tell you."

"Does he know where Piper is? Have you asked him? Did he leave her somewhere safe?"

Drury opens his palms. "I can't answer those questions."

A woman enters the room, her hair freshly brushed and make-up applied. She's carrying a toddler in colorful leggings and a bright-red smock.

She admonishes her husband. "You shouldn't be talking in here, Dale. Not in front of the children."

Sarah Hadley is a tall, attractive woman in her early forties, dressed in a dark silk shirt, cashmere cardigan and designer jeans that might never have been worn.

"Phoebe, can you please feed Jessica?" she asks. "She wants Rice Krispies. Make sure she wears a bib."

Phoebe takes her sister, lifting her onto a booster chair.

Sarah insists on talking in the drawing room. The precisely furnished room has sofas and armchairs arranged around a walnut coffee table. A Christmas tree, decorated in white, fills the bay window.

Sarah perches on the edge of an armchair, hands on her lap, knees together. The whites of her eyes are threaded with tiny red veins and her breath smells of something sweet: a drink to steel herself.

"They've arrested someone," says Mr. Hadley. "They think he might know where Piper is."

"I didn't say that," says Drury. "At this stage it's not wise to speculate."

Sarah turns her head and stares past the Christmas tree into the garden. The sun has come out and turned the frosty lawn into a carpet of diamonds.

"Natasha was the strong one," she whispers. "If she couldn't survive, what hope is there for Piper?"

Her husband hushes her and reaches for her hand, but she withdraws it almost instinctively. They're an odd-looking couple. Sarah looks like a former beauty queen with flawless skin, seemingly devoid of pores and such artfully applied make-up that it appears almost non-existent. Dale is short and stocky with a moon face and acne scars.

Each seems to have reacted differently to the news. Dale has allowed himself to hope for the first time in a long while. Now he wants to be outside, kicking down doors, shaking the trees and yelling Piper's name from the rooftops.

Meanwhile, Sarah, who has spent three years publicizing Piper's disappearance, keeping her in the public eye, giving interviews, putting up posters and running a website, has been hollowed out by the news of Natasha's death.

I have seen hundreds of couples overwhelmed by loss. Some can look straight into each other's eyes without needing words. Others are like strangers sitting on a long-distance train. Some fall to the ground shrieking while others remain unmoved, seemingly devoid of emotion. Some blame themselves, and others search for someone to blame, while a few drink themselves into oblivion or pretend nothing has changed.

I can picture this couple lying side by side in bed at night, hollow in heart and soul, wondering if Piper is still alive, one abandoning hope, the other clinging to it-until today when the roles have been reversed.

I have been there. I have lain awake staring at the ceiling, my bones aching with exhaustion, knowing Gideon Tyler had taken Charlie, wondering if she was still alive. I have been visited by every shade of grief and know that it doesn't come in black or white.

Dale Hadley takes me upstairs to Piper's bedroom. He pauses outside the door, as though unwilling to cross the threshold.

"I haven't set foot in this room," he explains. "Not since she went missing. Piper had this thing about her privacy. She didn't like anyone invading her s.p.a.ce." He uses his fingers to make inverted commas around the last statement.

"She was secretive?"

"Aren't they all? Teenagers, I mean." He scratches his unshaven jaw. "We let her put a lock on her door, but we took it off after she and Natasha got into trouble. They went to a college-age party... there was an incident."

"I heard."

"We knew Piper had been drinking and we caught her with pills in her bag. That's why we grounded her. She wanted to go to the festival, but we told her no. She snuck out anyway. That's the last time... you know..." He sighs. "The last words she said were that she hated me."

"She didn't mean it."

"I know." He glances at the single bed. "We blamed Natasha. She was always a wild child. You know how girls like pretending to be grown-up, dressing in their mothers' clothes, tottering in high heels? Natasha acted like she was always grown-up. Precocious isn't the right word. She was trouble. We tried to separate them by sending Piper to one of those camps for troubled teens, but that didn't do any good."

"You tried to stop her seeing Natasha."

"Did we do the wrong thing?"

"You shouldn't punish yourself."

"Why not? Maybe it was our fault."

His eyes close in a delta of wrinkles. Dale Hadley, like Isaac McBain, has spent three years debating the "what if's" and "if only's." What could he have done? How could he have changed things?

Piper's room is exactly as she left it. Her desk has textbooks stacked smallest to largest and there are pictures pinned to a notice board, mostly of Natasha. It is a typical teenage girl's room, full of lip gloss, bracelets and acne creams. Nothing strikes me as being odd or out of the ordinary, except for the fact that none of the posters or photographs feature boy bands or s.e.x symbols.

Everywhere there is evidence of girlhood adventures: a jumble of novelty pens, knick-knacks, key rings and cheap jewelry. I run my fingers over the bookcase. One shelf contains cloth-colored notebooks.

"She liked writing," explains Dale, still standing in the doorway. "We found them all over the place after she'd gone-behind the radiator, under the mattress, in the cavity behind her drawers. Some were wrapped in masking tape so that her sister couldn't read them."

"You gave them to the police?"

"Of course." He sighs. "She wrote some hurtful things about the family. You know what teenagers are like. They love and hate in the same breath."

I pick up one of the journals. "Can I borrow these?"

"Go ahead."

He looks absentmindedly at his watch. "I have to make some calls. They'll have heard the news at work, but I should say something..."

He turns and leaves, walking like a man submerged in water.

Taking the journals, I cross the corridor to a small home office, which is the "mission control" center for the "Finding Piper" campaign. There are posters on the walls, along with newspaper clippings, emails and photographs of Piper in every stage of her young life.

One image shows her digging earthworms from a muddy bank, concentrating so hard that her brow is furrowed. It's an inconsequential moment frozen in time, but something about the way it is framed and displayed makes Piper seem almost deified, like a child chosen for a higher purpose.

I'm aware of someone else in the room. Phoebe is sitting on the office chair with her legs crossed, watching me intently.

"h.e.l.lo."

"h.e.l.lo."

"You must be Phoebe."

"How do you know my name?"

I tap the end of my nose.

"Are you a detective?" she asks.

"No."

"Are you looking for Piper?"

"I am."

"If you find her, will I still be invisible?"

"Pardon?"

"Do you think Mum will see me then?"

"You think you're invisible?"

"I'm not like Piper. She's the one people talk about. She's the one they want to see-not me or Ben or Jessica. We're invisible."

"I'm sure that's not true. Your mother loves you."

Phoebe rocks forward and puts her feet on the floor. From downstairs, I can hear her brother Ben calling her.

"Goodbye," she says. "I'm glad you can see me."

Sarah Hadley is not in the house. I find her outside in the garden hitting golf b.a.l.l.s into a practice net. Pieces of ice fly off the mesh every time a ball smacks into the hanging curtain. I can imagine her in the summer at her country club, her long tanned legs in tailored shorts.

She drives a ball, wrapping the club around her back and holding the pose. Her shirt rides up over her flat stomach.

"Nice swing."

"I used to play on the county team."

At first glance her complexion had looked golden and almost unblemished but now I notice the skin around her eyes has been tightened. Repairs have been done. She takes a swig of something from a gla.s.s. Alcohol has glazed her eyes but hasn't numbed anything else.

"Maybe you should ease up on that," I tell her.

"Bit late now. I was two years sober until this morning."

"I could give you someone to call?"

"Therapy? Tried that too. None of it lasts."

"Where is your husband with this?"

"He makes excuses for me. He's not one to complain."

She swings at another ball and this one shanks to the right. "You know the saddest thing about all this?"

"What's that?"

"Phoebe doesn't know how to ride a pushbike because we haven't taught her. She's never taken the school bus or walked to the shops by herself. I'm scared that if I let her out of my sight she might not come back."

"That's understandable," I say, remembering my conversation with Phoebe.

"It's affecting her, you know. Little by little, I see her regressing. She was always a strong-willed little madam, but now I've made her helpless. She has nightmares, wakes up crying and shouting. Dale has to calm her down."

"Not you?"

"She doesn't settle so easily for me. You should see her bedroom. She kept every single one of the soft toys that people sent. The attic is bursting with them. Dale wanted to donate them to charity, but Phoebe wouldn't let him."

Sarah glances over her shoulder at the house, proud of her family but unable to explain the mix of feelings that marriage has brought her. The Christmas tree is visible through the drawing room window.

"We still hang Piper's stocking every year. And we have a cake on her birthday, with just the right number of candles. We've been going through the motions, but now it seems more real... more real than yesterday."

She tees up another ball, checks her grip, makes a practice swing.

"I've grown used to being stared at. People whisper behind my back-they think I'm a publicity-seeker. Phoebe came home from school one day and said a boy had told her that Piper was dead and that I should shut up and stop talking about her.

"That's what people think. They think our little girl was murdered or ran away because we were awful parents. They think I waste my time, banging on pointlessly... putting up posters, not letting them forget. Do you know why I've never given up?"

"No."

"I talked to a medium... a psychic. She told me that Piper and Natasha were still alive. She said they were together and were trying to get home. She said, "They are beneath the earth, but not a part of it. Breathing in the darkness."

"How did you meet this medium?"

"Vic McBain was going out with her."

"Natasha's uncle?"

Sarah nods and something feverish pa.s.ses across her face. She doesn't strike me as being the sort to hang her hopes on the cold reading capabilities of a psychic, but three years is a long time without news and desperation is a cold cup of coffee.

"What else did this medium say?"