Ryan Whitmore thought his seven-year-old son was feeding mice.

That was the only explanation that made sense when he walked into the kitchen of the Whitmore estate and found Leo sitting cross-legged on the marble floor, tearing a turkey sandwich into tiny pieces.

One piece disappeared through the old brass vent near the base of the wall.

Then another.

Ryan set his briefcase beside the kitchen island.

"Leo."

The boy jumped.

A piece of bread fell from his fingers.

Ryan loosened his tie and looked toward the vent.

"What are you doing?"

Leo glanced at the doorway before answering.

It was a strange reaction.

Almost as if he were checking to make sure they were alone.

"Nothing."

"You're feeding something."

Leo shook his head.

Ryan walked closer.

He had returned to Scarsdale nearly four hours earlier than expected after a meeting in Manhattan was canceled. Claire didn't even know he was home yet.

He crouched beside his son.

"Mice?"

"No."

"Then what?"

Leo stared at the sandwich.

Ryan waited.

Finally, the boy whispered, "She's hungry."

Ryan frowned.

"Who is?"

"The girl."

For a moment, Ryan thought he had misheard him.

"What girl?"

Leo pointed at the vent.

"The little girl behind the wall."

Ryan stared at his son.

Leo had always had an active imagination, but this wasn't the way he usually told stories. There was no excitement in his voice.

There was fear.

"There's no girl behind that wall."

"Yes, there is."

"Leo."

"I hear her at night."

Ryan's smile disappeared.

"What do you mean?"

"She cries when it gets dark."

A chill moved slowly across Ryan's shoulders.

He looked at the vent again.

The kitchen had been renovated before he and Claire moved into the estate seven years earlier. Ryan knew there were old maintenance shafts behind several walls, remnants of the original 1920s construction.

But none were large enough—

A faint sound came from behind the vent.

Ryan froze.

It sounded like scratching.

Leo immediately leaned forward.

"Sophie?"

Ryan looked sharply at him.

"You know her name?"

Leo nodded.

"She told me."

Another sound came from inside the wall.

This time there was no mistaking it.

A cough.

Small.

Weak.

Human.

Ryan dropped to one knee and reached for the vent.

"Ryan!"

Claire's scream cut through the kitchen.

He spun around.

His wife stood in the doorway.

Her face had gone completely white.

She wasn't looking at him.

She was looking at his hand.

At the vent.

"Don't touch that."

Ryan slowly stood.

"What?"

Claire rushed toward him.

"Ryan, please. Just leave it alone."

He stared at her.

Seven years of marriage had taught him every version of Claire Whitmore.

The composed wife at charity dinners.

The affectionate mother helping Leo with homework.

The woman who could smile through an argument and wait until they were alone to tell him exactly how angry she was.

He had never seen this woman.

Terrified.

"What's behind the wall, Claire?"

"Nothing."

Leo looked up.

"Mom knows."

Claire's eyes snapped toward him.

"Leo."

The warning in her voice was unmistakable.

The boy shrank back.

Ryan stepped between them.

"What does he mean?"

"He's confused."

"No, I'm not!"

Leo's voice cracked.

"She gets hungry when Mom forgets to feed her."

The room went silent.

Ryan felt as if someone had struck him in the chest.

He turned slowly toward Claire.

"What did he just say?"

Tears filled her eyes.

"Ryan, listen to me."

"Is there a child behind that wall?"

"It's not what you think."

That answer was worse than a denial.

Ryan moved toward the vent.

Claire grabbed his arm.

"No!"

He pulled free.

"Get out of my way."

"You don't understand."

"Then make me understand."

"Not like this."

"There's a child in my wall!"

His voice thundered through the kitchen.

Leo covered his ears.

Ryan immediately regretted shouting in front of him, but before he could speak, another noise came through the vent.

A whimper.

Then a voice.

"Please."

Ryan's blood turned cold.

He dropped to the floor.

"Can you hear me?"

Nothing.

He moved closer.

"My name is Ryan. I'm going to get you out."

Claire began crying.

"Ryan, don't."

He looked over his shoulder.

"Why?"

She said nothing.

"Why don't you want me to open this?"

"Because once you do, nothing goes back to the way it was."

Ryan stared at her.

Then something moved between the metal slats.

Five tiny fingers appeared.

Pale.

Dirty.

Trembling.

Leo began to cry.

"See? I told you."

Ryan's hands shook as he touched the vent.

"Sweetheart, can you hear me?"

The fingers curled around the metal.

"Yes."

The voice sounded painfully weak.

"Are you hurt?"

"My stomach hurts."

Ryan closed his eyes for half a second.

When he opened them, whatever confusion remained had been replaced by fury.

He stood.

"Leo, go upstairs."

"But Sophie—"

"Go to your room. Now."

"I was just trying to feed her."

"I know."

Ryan softened his voice.

"You did the right thing. Go upstairs and stay there until I come get you."

Leo wiped his face and ran from the kitchen.

Ryan waited until his footsteps disappeared.

Then he faced Claire.

"We're opening the wall."

"No."

"If you try to stop me again, the first call I make is to the police."

Claire's lips trembled.

Ryan pulled open a utility drawer and grabbed a screwdriver.

He knelt.

The first screw came loose.

Then the second.

"Ryan."

He ignored her.

"Please."

Third screw.

The vent shifted.

Claire sank against the island.

Ryan pulled the metal grate away.

Behind it was darkness.

A little girl stared back at him.

She couldn't have been older than six.

Her blond hair was tangled around a thin face. She wore an oversized gray sweatshirt, and her knees were pulled tightly against her chest.

There was a bottle of water beside her.

Two empty snack wrappers.

And a folded blanket.

Someone had put her there.

Ryan's stomach turned.

"Jesus Christ."

The girl blinked at the light.

Ryan reached toward her.

"It's okay. I'm going to get you out."

She stared at his face.

Something changed in her expression.

Confusion.

Recognition.

Then tears.

"Dad?"

Ryan stopped breathing.

Behind him, Claire made a broken sound.

He slowly turned toward his wife.

She was covering her mouth.

"No."

Ryan stood.

"Who is she?"

Claire shook her head.

"Ryan—"

"Who is that little girl, and why did she just call me Dad?"

Claire's knees nearly gave out.

Ryan had never seen fear like that.

Not even when Leo had been rushed to the emergency room at three years old.

This was different.

This was guilt.

"Tell me."

Claire closed her eyes.

When she finally spoke, her voice was barely audible.

"She's the reason I knew you'd leave me."