This is part of an original serialized fiction project written and edited by the author. All story elements and characters are fictional.

Lucia looked at the house, noticing that the windows were boarded up and the front door was partially down.
"It doesn't look like anyone's lived here in a long time."
"That doesn't mean there isn't something useful inside," Teodora replied, walking toward the entrance.
The house was dark and quiet, with the smell of dampness permeating the air. Her footsteps echoed on the wooden floor, which creaked under her weight. Lucia turned on her flashlight, illuminating the dusty furniture and the walls lined with torn papers.
"This is a little spooky," she said, trying to sound casual.
Leo inspected an old desk in the corner of the main room, carefully opening the drawers.
"There's not much here... just old papers and..." He stopped when he found a small notebook, covered in worn leather. "What is this?"
Teodora walked quickly over, taking the notebook from Leo's hands.
"Could be a diary," she said, flipping through the pages.
The first entries were brief notes about the house's maintenance, but as they progressed, the words became more cryptic.
"The echo must not be forgotten. If what lies beneath the spiral is found, the balance will be broken."
Lucía leaned over Teodora's shoulder to read.
"'Under the spiral'? That symbol again?"
Teodora frowned, quickly flipping through the pages.
"This confirms that Cárdenas knew something about what was in the Esmeralda building. And it seems he was worried about what might happen if someone found it."
Leo turned to a small bookshelf along the wall.
"Do you think he was working alone? Or were the Keepers still in contact?"
"It's hard to say," Teodora said, closing the notebook. "But there's something else here. I know there is."
As they searched for more clues, Lucía noticed that a section of the floor was slightly raised, as if something were underneath.
"Look at this!" she said, kneeling down to inspect the loose wooden board.
Leo joined her, helping her carefully lift it. Underneath, they found a small compartment containing a metal box locked with a padlock.
"This looks important," Leo said, pulling the box out.
Teodora examined it, noticing that the padlock was engraved with the same spiral symbol they had seen before.
"It's from the Keepers group," she confirmed, running her fingers over the engraving.
Lucia frowned.
"How do we open it?"
Teodora took a tool from her bag, but Leo stopped her.
"Wait. If it's sealed with that symbol, couldn't it be protected somehow?"
Teodora looked at him in surprise, then nodded.
"Good observation. It could be linked to the artifact or the Echo Chamber."
Lucia looked at the box, uneasy.
"What if opening it triggers something?" "We won't do it here," Teodora said, putting the box in her bag. "First, we need to make sure it's safe."
By the time they left the house, the sunlight had completely faded, leaving only the light from their flashlights to illuminate the path.
"This was more productive than I expected," Teodora said, looking at the notebook and the box.
"But how useful will it be?" Lucía asked. "If Méndez knows about this place, he might have found something similar."
Leo stopped suddenly, staring down the dark path that led them back to the highway.
"Did you see that?"
"What thing?" Lucía asked, turning quickly.
"A car. I thought I saw lights up ahead."
Teodora pressed her lips together, feeling a sense of urgency.
"We can't stay here. If someone is following us, we need to get back to the building as soon as possible."
The three of them began to walk faster, their footsteps echoing in the silence of the night.
As they reached the road, the headlights of a vehicle appeared behind them, moving slowly.
"It's Méndez!" Lucía exclaimed, her heart racing.
Teodora eyed the car cautiously and then pointed to a small side road.
"Quick, this way!"
They ran toward the path, disappearing into the trees as the car's headlights briefly illuminated the spot where they'd been.
"Do you think he saw us?" Leo asked, panting.
Teodora shook her head, though her expression remained serious.
"I don't know, but we can't let our guard down. This is just the beginning."
When they finally returned to the Esmeralda building, the three of them were exhausted but relieved to have escaped. Teodora placed the box and notebook on the apartment table, looking at the siblings.