"I left Amanda with her. She's alone with my little girl." Bonnie bolted for the door.

"I tried to be her friend," Bonnie heard the woman who fancied herself Jacqueline Kennedy Ona.s.sis cry out as she ran down the hall. "I could have helped that girl, if only she'd let me."

Bonnie drove like a maniac along Route 20, watching as Boston Post Road became State Road West, then State Road East back into Weston, where once again it became Boston Post Road. She was shivering, sweating, crying, shouting. "No, it can't be," she kept repeating. "It can't be."

Bonnie recalled how eager Lauren had been to visit her grandmother, how touched she'd been when the old woman spoke her name, how loving she'd acted toward her, sitting beside her on the bed, feeding her lunch. Could she have returned at a later date to feed her poison? When? The girl had school all day. When would she have had the opportunity?

"She stayed home from school one day," Bonnie said out loud, remembering the day that Lauren had felt queasy, thought she might be suffering a relapse of the flu. Except that it wasn't the flu. It was a.r.s.enic.

Unless she hadn't been sick at all. Unless she was merely pretending.

"No, that's impossible," Bonnie said. "I saw how sick she was. I held her head for hours while she threw up. That was no act. She was really sick."

But she got better, Bonnie thought. While I got sicker and sicker. And she was always there. She was always there.

But why? Bonnie wondered, screeching to a halt at the red light at the corner of Boston Post Road and Buckskin Drive, looking around impatiently, tapping her foot against the gas pedal. "Why would she want to kill me?"

Bonnie thought back to the afternoon she and Rod first went to Joan's house to tell Lauren and Sam about their mother's death. She remembered Lauren's violent outburst, felt the sharp jab of Lauren's shoes against her shins, the hard smack of her fist against her mouth. She hates me, Bonnie recalled thinking.

But surely that had changed. Surely over the ensuing weeks, they had moved closer, forming a bond of respect and friendship. Unless that too had been an act.

But even if she hates me, Bonnie thought, does she hate me enough to want me dead? And why would she want to kill her grandmother, a helpless old woman who barely remembered who she was?

And who else? Bonnie wondered, her foot flooring the gas pedal as the light turned green, the car streaking across the intersection, as if someone had inadvertently pressed the fast forward b.u.t.ton on a VCR.

Bonnie tried desperately not to think at all, to concentrate on the road ahead. Her thoughts were too bizarre, too crazy, more like drug-induced fantasies than anything connected to reality. Was she actually thinking that Lauren might have had something to do with her mother's murder, with Diana's death?

"No, this is ridiculous. You're being absolutely ridiculous."

Lauren was at school the day her mother was murdered. She was at home the morning Diana was killed. Wasn't she?

She could easily have skipped a cla.s.s or two, Bonnie realized. The police wouldn't have bothered to check. Who would suspect a fourteen-year-old girl of killing her mother? And she could have easily slipped out of the house to kill Diana while Rod was asleep. She knew where Diana lived. She'd certainly been there before.

But why? Why would she want to hurt Diana? And what motive could she have had for wanting her mother dead?

You're in danger, Joan had warned her. You and Amanda.

Was Lauren the danger Joan had been trying to warn her against?

"Oh my G.o.d." Bonnie pictured her daughter's innocent hand inside that of her half sister's. "Don't you hurt my baby. Don't you dare hurt my baby." She turned right onto Highland Street, the scenery blurring into a green fog as she accelerated along the clear road. "Please don't hurt my little girl," she prayed out loud.

How could she have left her daughter alone with Lauren? Hadn't Joan cautioned her enough times never to use her children as baby-sitters? Maybe those p.r.o.nouncements hadn't been the drunken ramblings of a jealous ex-wife at all. Maybe Joan had been trying to warn her even then.

But why?

Always why.

It didn't make sense. It wasn't possible. Lauren couldn't have had anything to do with either her mother's death or Diana's, with Elsa Langer's poisoning or her own. Yes, she had access to her mother's gun; yes, she must have known where her mother kept the rat poison. But that didn't mean anything necessarily. So did Sam. So did Rod.

Except that both Sam and Rod were at the police station, and Lauren was with her little girl.

Lauren had taken Amanda to the park, but which park? There were several in the area, and they could have gone to any one of them. "Where are you, d.a.m.n it?" Bonnie demanded. "Where did you go?"

She drove past Brown Street, inadvertently glancing toward Diana's house, saw the now-familiar yellow tape cordoning off the house. Crime scene. Do not cross. "Don't panic," she told herself, turning right on South Avenue, seeing the little park at the corner of South and Wellesley, slowing to a crawl.

Some children were playing on the swings and slides, watched over by several bored-looking women, but Lauren wasn't among them, and neither was Amanda. Bonnie thought of stopping, of asking the women if they'd seen her child, but she didn't recognize anyone, and didn't want to waste any time. She doubted she would be able to speak with any coherence anyway.

Where else might they have gone? There was a little park back on Blueberry Hill Road, but it was tiny and had only a few swings, and Amanda didn't like it much. And there was the playground behind her school, the playground beside the small alleyway that was Alphabet Lane, where someone had emptied a pail of blood over Amanda's head. "Oh G.o.d," Bonnie moaned. Surely, Lauren wouldn't try to hurt her now, not so soon after Diana's murder.

Bonnie sped up Wellesley Street to School Street, turned left. She tore up the long driveway of the combination school-day care center, jumping out of the car in the same second she pulled the key from the ignition, running along the small walkway to the back of the school, the fully equipped playground popping into view.

There was no one there. Bonnie spun around. "Where are you?" she cried. "G.o.dd.a.m.n it, Lauren, where did you take my baby?" And then she saw it, discarded in the sand at the foot of one of the swings. She raced toward it, bent down, scooped the bright pink Barbie bag into her hands. So, they'd been here. Been and gone. Was it possible they'd returned home?

Bonnie raced to her car, almost skidding into a tree at the side of the road as she backed it onto the street. "Slow down," she told herself, easing her foot off the gas pedal as she made a sharp right turn onto Winter Street. "You're almost there."

The house appeared at the second bend in the road and Bonnie pulled into the driveway and jumped from the car. "Amanda!" she called even before she reached the front door. "Amanda! Lauren!" She fumbled with her key and pushed open the door, tripping over her feet into the front hall, taking the stairs two at a time.

She saw the blood as soon as she reached the upstairs hall. Just a few red drops on the white tile of the bathroom floor, but they were unmistakable nonetheless. "Oh my G.o.d." Bonnie threw her hand across her mouth to keep from screaming. "No, please, no." Slowly, as if her feet were encased in cement, she approached the bathroom.

And then she heard a tiny squeal from behind the closed door to Amanda's bedroom and she spun toward the sound. "Amanda?" she cried, her voice as shaky as a single tear. Her hand reached toward the door, gently pushed it open, her breath stilled in her lungs, her eyes afraid to focus.

Amanda was sitting cross-legged on the floor in the middle of the room, one hand on her knee, the other extended toward Lauren, who sat beside her, her tote bag in her lap, holding Amanda's wrist in one hand, a razor blade in the other.

"Oh my G.o.d."

"Please don't come any closer," Lauren said simply.

"I fell, Mommy," Amanda told her, lifting her hand from her freshly sc.r.a.ped knee. "Lauren was pushing me on the swing, and I fell off and hurt my knee. I was crying, but Lauren told me not to cry, and she cleaned it up for me."

"I'm sorry the bathroom's such a mess," Lauren said, as if this were the most normal conversation in the world, as if she weren't holding a razor blade to Amanda's wrist.

"Amanda," Bonnie began, her eyes glued to her daughter's delicate veins, "why don't you go downstairs and get some milk and cookies...."

"Not now, Amanda," Lauren said with authority. Amanda didn't move.

"Lauren says we're going to become real sisters. Blood sisters," Amanda emphasized. "She said it wouldn't hurt."

Bonnie felt the air around her suddenly turn to ice. Her breath had to fight its way through. "What?"

"What did Mary have to say?" Lauren asked. "I know you went to see her. She told you I was there, didn't she?" Her voice a.s.sumed a faraway cadence, as if she were speaking from another room.

"Yes." Bonnie took a step forward.

"I wouldn't come any closer," Lauren said. "I might get nervous. My hand could slip."

Bonnie stopped dead. "Don't hurt her," she begged. "Please don't hurt her."

"Lauren said it wouldn't hurt, Mommy. Not like when I sc.r.a.ped my knee."

"That's right, Amanda." Lauren gave her hand a little squeeze. "I wouldn't do anything to hurt you. You're my little sister."

"Please," Bonnie begged. "Let go of Amanda's hand. Let's talk. I'm sure that we can work everything out."

"What if I don't want to talk?"

"Then we don't have to talk," Bonnie agreed immediately. "We don't have to say anything."

"Just wait for the police to get here so you can talk to them?" Lauren asked.

"I have nothing to say to the police."

"No? That's strange. I thought you'd have a lot to tell them."

"No," Bonnie said. "Nothing."

"I killed them, you know," Lauren said evenly. "I killed all of them."

Bonnie felt her heart grow heavy and sink into the pit of her stomach. "You killed your mother?" she asked, though the question had already been answered.

Lauren's voice turned petulant. "It was her own fault. If she hadn't gone snooping in my room, she never would have found my sc.r.a.pbook. That's what started it all."

"The sc.r.a.pbook was yours?"

Lauren nodded. "Pretty neat, huh? I started keeping it the day you married my father."

"But why?"

A cloud pa.s.sed across Lauren's eyes, threatened rain. "My father loves me, you know. He's always loved me. Even when he went away. Even when you tried to take him away from me."

"Lauren, honey, I never tried to keep your father away from you."

"You tried," Lauren insisted. "Everybody tried. But I wouldn't let them."

Bonnie tried desperately to make sense of what she was hearing, her eyes never leaving her daughter's delicate wrist. Perhaps if she could keep Lauren talking long enough, she'd loosen her grip. "That's why you shot Diana?"

"She was really something, wasn't she? Pretending to be your friend. Sneaking around behind your back. s.c.r.e.w.i.n.g my father. You know when I found out?"

"When your father showed up at Diana's?"

"No." Lauren shook her head. "I had it figured out way before then. I knew the first time Sam and I went over there, the time Amanda was with us. You know what Amanda found when she was looking through Diana's dresser? You found all sorts of s.e.xy undies, didn't you, Amanda?"

The child nodded, mesmerized, though clearly confused by the direction the conversation had taken.

"You know what else she found?" Lauren continued. "Those silly little scarves, like the kind you had tied around your wrist that night I was so sick. The same kind of scarves my father tied you to the bed with when you were having s.e.x."

"Mommy, why did Daddy tie you to the bed?" Amanda asked, eyes like saucers.

Bonnie lowered her eyes to the floor, the memory of that night filling her head, like the smell of rotting fruit.

"G.o.d, that made me sick," Lauren said. "Almost as sick as the a.r.s.enic."

"You gave yourself a.r.s.enic?"

"Smart, huh? I saw it in a movie once. That way you never suspected it was me, even after you found out you were being poisoned. Of course, I had to do it gradually. I could only give you a little bit at a time, so everyone would think it was the flu."

"And you put the snake in Amanda's bed," Bonnie stated rather than asked.

"He was supposed to wrap himself around her neck and give a little squeeze, but it didn't work out that way. It was no big deal. I knew I'd get another chance. Accidents happen to little kids all the time. Like falling off a tricycle. Or a swing." She laughed. "Besides, it was fun watching you worry."

"Is that why you threw the blood on her? So I'd worry?"

Lauren smiled at Amanda. "You should have seen her before they cleaned her up. She was quite a sight."

"You threw blood on me," Amanda repeated indignantly, trying to pull away. "I don't like you anymore."

"Come on, Mandy," Lauren cajoled, tightening her grip on Amanda's wrist. "You're not afraid of a little blood, are you? I thought you were a big girl."

"I don't like you anymore. You're not nice. I don't want to be your sister." Again she tried to pull away.

Lauren quickly lifted her onto her lap, held the razor to her throat.

"Please, no!" Bonnie cried. "Please don't hurt her. Don't move, baby," she cautioned her squirming child.

"It's all your fault, you know," Lauren told Bonnie.

"My fault?"

"You were supposed to get arrested for killing my mother. Then I could have moved in with my father, and taken my time about getting rid of Amanda. It would have been much simpler. I wouldn't have had to hitchhike and take all those d.a.m.n cabs back and forth everywhere. I wouldn't have had to ask Haze to get me the blood." She giggled. "He's such a jerk. He thought we were just playing games. He even fixed your car so it wouldn't start."

Tears began falling down Amanda's face, one veering off, distracted by the tiny scar along her cheek. "Don't cry now, baby," Bonnie told her, wondering if there was some way to distract Lauren, to get Amanda to safety.

"What about Sam?" she asked, playing for time. "Was he involved?"

"Are you kidding? Sam thinks you're the greatest thing since Leggo." She made a sound halfway between a laugh and a cry. "It must have been some shock when he went to collect his money and found Diana dead on the floor."

Amanda fidgeted in Lauren's tight embrace. The razor pressed deeper into her throat. A tiny dot of blood appeared.

"Please," Bonnie begged, "you don't want to hurt Amanda. You don't really want to hurt her. She's your baby sister."

There was silence.

"I don't want a baby sister," Lauren said, her voice cold and hard, like the granite of a tombstone. "I never wanted a baby sister."

Bonnie felt her entire body go numb as the realization of exactly what Lauren was saying began seeping its way into her bones. "What are you saying?" she asked slowly.

"I think you know."

Bonnie shook her head back and forth. "Are you telling me that you killed Kelly? That her death wasn't an accident?"