Ava examined the lower edge of the unit. A fresh scratch ran across its mounting screws, and a short cable hung loose inside the cracked plastic seam.

That cable had not been loose yesterday. Her stomach turned as she remembered Vivian supervising a contractor near the pool’s control cabinet that very afternoon.

Vivian had smiled when Ava asked questions. “A little maintenance,” she had said. “Don’t worry yourself about grown-up decisions.”

Lily leaned against the wall and coughed again. Ava opened a linen cabinet, grabbed the largest dry towel, and wrapped it securely around her sister’s shoulders.

The little girl’s fingers clutched the towel’s edge. Ava rubbed her back gently, searching the vast room for an alarm, a usable phone, anything that could reach another person.

Her own phone was in her back pocket. She pulled it free and pressed the side button, but the screen remained black beneath a sheet of trapped water.

Ava stared at the dead screen, furious with herself for bringing it into the pool. Then she remembered that Grace had always taught her to solve one problem at a time.

She scanned the ceiling. A red emergency strip glowed along the south wall, fed by its own battery. Somewhere beyond that wall ran the old maintenance corridor.

The mansion was built long before Vivian arrived. Ava had explored its servant staircases as a child, racing her father from one hidden doorway to another.

A brass plaque near the towel cabinets still read MECHANICAL ACCESS. Below it sat a narrow metal service panel, half concealed by a decorative bench.

Ava set Lily on the bench and checked her breathing again. The child was alert, but frightened and cold; every passing minute made Ava’s need for help more urgent.

“Stay right beside me,” Ava said. “I’m not leaving you. I just need to see whether somebody can hear us through this wall.”

She dragged the bench away, its feet scraping loudly across marble. Behind it, a small inspection grille covered a dark passage barely wide enough for a person.

Ava struck the grille with the heel of her palm. The noise boomed down the pipework, and both sisters froze, listening for an answering sound.

Nothing came. Beyond the glass entrance, the long hallway stayed empty, displaying perfect chandeliers and the polished quiet of a house hiding something terrible.

Then Lily gripped Ava’s sleeve. “She said you couldn’t find me,” the child whispered. “She said you’d go away, too.”

Ava felt the words hit harder than cold water. She knelt beside Lily and held her face gently, forcing herself to speak without letting her voice break.

“I’m not going away,” she said. “Not tonight. Not ever because somebody tells me to. You and me, Lily. Always.”

From behind the inspection grille came a faint metallic vibration. Ava leaned closer. It sounded like an old pipe, or footsteps moving slowly on the other side.

She hammered three deliberate blows against the metal. The vibration stopped. For several seconds, nothing moved at all, until someone answered with two unmistakable knocks.

Ava turned toward Lily, hope flashing through her fear. She had no idea who was beyond that wall, but they were not alone anymore.

Chapter 2 – THE VOICE BEHIND THE WALL