Night had completely enveloped the Eastern District.
The cold wind swept between the buildings.
On the sixth floor of the commercial office building, the manager's office remained illuminated, unchanged from the previous several days.
Lucian slowly withdrew the Azure from his palm.
The pale blue mist that had covered the entire building began to converge, little by little, before finally disappearing into his palm.
The night wind returned to its former calm.
Yet the complete structural analysis of the building remained preserved in his mind.
The hidden space did exist.
Its location was between the fifth and sixth floors.
It was neither an illusion nor a phantom created by an ability.
It was a real, enclosed space concealed within the building.
However, confirming its existence did not bring any visible relief to Lucian.
Finding the space merely meant that the investigation had entered its next stage.
The real question had never been whether the space existed.
It was how to enter it.
He did not rush to activate his ability again. Instead, he stood in the night wind and methodically reviewed all the information he had just obtained.
First, he eliminated every possibility involving access from outside the building.
The Azure had already covered the entire commercial office building.
The exterior walls.
The glass curtain walls.
The load-bearing columns along the outer walls.
The fire escape platforms.
The external air-conditioning units.
The drainage pipes.
Even every metal bracket connecting the building's structural components.
Everything had been analyzed.
The hidden space was completely enclosed by the main structure of the building.
None of its sides came into direct contact with the exterior walls.
Nor was there any concealed entrance that could be opened from outside.
If the entire building were compared to a cube, then the hidden space was like another completely enclosed box placed inside it.
All around it were concrete, steel reinforcement bars, and load-bearing beams.
There were no windows.
No ventilation openings.
And no structural passage leading to the exterior.
Lucian closed his eyes again.
The structural diagram obtained during the initial scan gradually reappeared in his mind.
His thoughts did not remain focused on the sixth floor.
Instead, he began reconstructing the entire building from the beginning.
The rooftop.
He eliminated it first.
If the hidden space could be accessed from the roof, the Azure would have already detected a vertical passage connecting the upper and lower levels.
But the rooftop structure was completely intact.
Apart from the elevator machinery room, air-conditioning equipment, and ordinary maintenance areas, there were no additional spaces.
Next came the fire escape.
Every fire escape platform followed the same structural design.
The stairwell extended continuously through all the floors.
There were no deviations.
Nor was there any possibility of a passage branching off toward the hidden space midway down.
Then came the building's exterior.
From the glass curtain walls to the supporting framework, including every location where maintenance personnel could stand, there was no mechanism capable of opening an entrance.
The entire building was like a single, solid structure.
It offered no opportunity for anyone to enter the hidden space from outside.
Lucian even reviewed the surveillance records from the past several days.
The technician had practically overlooked no exit.
The main entrance.
The side doors.
The underground parking garage.
The fire escape routes.
The rooftop.
Every possible route in and out had remained under surveillance.
If the entrance to the hidden space were located outside the building, the manager could not have gone four consecutive days without leaving a single trace.
At that thought, Lucian slowly opened his eyes.
The office on the sixth floor remained illuminated.
It was quiet, as though nothing had ever happened.
A conclusion had now fully taken shape in his mind.
The hidden space was real.
Yet there was no way to enter it from outside the building.
That left only one answer.
The entrance had to be inside the building.
And it could only be opened from within.
This was not speculation.
It was the only conclusion that could naturally be drawn after completing a full structural analysis of the entire building.
Having established this, Lucian did not continue releasing the Azure.
Instead, he stood silently where he was.
He began recalling every detail from his visit to the commercial office building earlier that day.
This time, he was no longer reviewing the manager.
He was reviewing the building itself.
From the moment he entered the lobby until he left the sixth floor, every layout he had seen, every corridor, every room location, and every spatial proportion was reconstructed and organized in his mind.
Because now, the real question was no longer who had entered the hidden space.
It was how the hidden space was connected to the building in the first place.
...
The images in his mind began to overlap.
The lobby.
The elevator.
The sixth-floor corridor.
The document management company.
The manager's office.
Every scene he had witnessed during the day gradually aligned with the three-dimensional structural model produced by the Azure.
He no longer bothered recalling the manager's every movement.
When the manager stood up.
When he looked through documents.
When he organized files.
None of those details mattered anymore.
Now that the entrance had been confirmed to lie somewhere inside the building, the only thing worth examining again was the building itself.
His memories began moving backward through the route he had taken.
The sixth-floor office area.
The manager's office was situated at the very back, directly against the building's exterior.
The office area as a whole was spacious.
The desk, reception area, filing cabinets, and sofa were all arranged naturally.
During his first visit, nothing had seemed unusual.
But as the three-dimensional structural model continued to overlap with his memories of the actual location, an extremely subtle inconsistency gradually emerged.
The manager's office.
It seemed slightly larger than he had originally judged.
The difference was minute.
Almost impossible to notice with the naked eye.
The furniture arrangement cleverly distorted a person's perception of the available space.
But the structural analysis provided by the Azure could not lie.
Spatial dimensions were fixed data.
Lucian did not rush to a conclusion.
Instead, he continued recalling the route he had taken after entering the elevator that morning.
The sixth floor.
The manager's office.
Directly below it.
A different company occupied the corresponding area on the fifth floor.
Although he had not entered the fifth floor, its structure had already been recorded in his mind during the scan of the entire building.
An office occupied the corresponding position there as well.
However, its layout differed from that of the sixth floor.
Under normal architectural design, corresponding areas on adjacent floors generally shared consistent structural features.
Load-bearing columns, walls, and floor slab thicknesses would ordinarily remain aligned.
Even if different tenants renovated their respective offices, the main structural framework would not change.
Yet there was a slight discrepancy between the corresponding areas on these two floors.
The manager's office on the sixth floor was slightly larger.
The corresponding area on the fifth floor was slightly smaller.
Viewed individually, both companies' offices appeared perfectly normal.
Nobody would become suspicious over a difference of a few square meters.
But when the two floors were compared side by side, the discrepancy became unnatural.
Lucian activated the Azure once more.
This time, however, he reduced its coverage to the absolute minimum.
The pale blue mist passed through the night and returned to the sixth floor.
It no longer spread across the entire office area.
Instead, it moved directly toward the vicinity of the manager's office.
There was only one objective.
Find the precise point where the hidden space connected to the building.
The Azure slowly penetrated the walls.
It passed through the floor slabs.
The fifth floor.
The hidden space.
The sixth floor.
All three structural layers appeared simultaneously in Lucian's mind.
He did not continue scanning the interior of the hidden space.
Instead, he began searching for the connections between these structures.
The load-bearing columns.
No abnormalities.
The steel beams.
No abnormalities.
The concrete walls.
They all retained the structure of an ordinary commercial building.
Lucian controlled the Azure as it moved slowly along the perimeter of the hidden space.
Its progress was far slower than during the initial scan.
It advanced almost inch by inch.
Not a single area that might come into contact with the hidden space was overlooked.
With every section it passed, a mass of structural information flowed back to him.
Ordinary walls.
Ordinary floor slabs.
Ordinary steel reinforcement.
Every reading matched the structure of a normal office building.
Time passed, little by little.
Lucian remained patient.
He knew that whatever had been deliberately concealed would never reveal itself easily.
Finally, when the Azure reached the innermost wall of the manager's office, the information it returned changed.
An extremely fine metal structure appeared deep inside the wall.
It was not a load-bearing component.
Nor was it a bolt securing a cabinet in place.
It was an independent mechanical transmission system.
The entire assembly lay tightly against the cast concrete.
Its dimensions were small.
It was almost indistinguishable from the surrounding steel reinforcement.
An ordinary scan could easily mistake it for a structural fixture.
But as the Azure continued its analysis, the mechanical structure did not end there.
It extended through the wall.
Then continued farther back.
Eventually, it connected to the hidden space between the fifth and sixth floors.
Lucian expanded the analysis range again.
He quickly confirmed that there was only one mechanical connection around the entire perimeter of the hidden space.
There was no second connection anywhere else.
His gaze returned to the distant sixth floor.
The conclusion in his mind settled into place.
The search area for the entrance had finally narrowed.
The only point connected to the hidden space was located at the innermost part of the manager's office, close to the wall.
...
After confirming the connection point, Lucian did not immediately withdraw the Azure.
Now that he had found the hidden space's sole connection, the next question was no longer where the entrance was.
It was how the entrance could be opened.
The pale blue mist stopped spreading outward.
Instead, it slowly seeped into the innermost section of the manager's office.
The desk.
No abnormalities.
The sofa.
No abnormalities.
The bookshelf against the wall.
Its interior consisted of nothing more than ordinary wooden components.
Only when the Azure extended farther did the filing cabinet come into its range of perception.
Lucian did not analyze the documents stored inside.
Their contents were irrelevant to the investigation at this stage.
What interested him was the cabinet itself.
The doors.
The shelves.
The metal supports.
The wooden backing.
Its structure unfolded layer by layer.
Every component was indistinguishable from that of an ordinary office cabinet.
If he had not already confirmed the existence of the sole connection point, anyone would have assumed this was nothing more than an ordinary filing cabinet.
The Azure continued penetrating deeper.
Beyond the wooden backing, a deeply concealed metallic structure finally appeared in his perception.
It was not a fastener holding the cabinet together.
It was a complete mechanical lock cylinder.
Its position was exceptionally ingenious.
It was entirely concealed behind the innermost row of archive boxes.
Under normal circumstances, someone would first have to remove several files from the back and then push a movable partition behind them before the keyhole could be exposed.
Without knowing its exact location, even someone who searched the entire office would have difficulty discovering that another mechanism was hidden here.
Lucian continued analyzing the interior of the lock cylinder.
The Azure slowly entered the keyhole.
The mechanical structure within unfolded layer by layer in his mind.
Locking plates.
Locking pins.
Springs.
Gears.
Connecting rods.
Every component was arranged with extraordinary precision.
As the analysis progressed, the mechanical assembly behind the lock cylinder gradually became clear.
It was not connected to any electrical wiring.
There were no sensors.
Nor was there any network control module.
The entire mechanism operated through purely mechanical transmission.
Behind the lock cylinder, a metal drive rod concealed within the wall extended backward.
It passed through the concrete and continued into the hidden space.
Eventually, it connected to the entrance mechanism.
There, several heavy mechanical locking bolts held a metal lifting platform firmly in place.
Only after a key was inserted into the lock cylinder and turned at the correct angle would the internal locking plates move into their designated positions.
The mechanical transmission would then activate the connecting rods.
The rods would release the locking bolts.
Once every bolt had been disengaged, the lifting mechanism would begin operating.
Even the seemingly ordinary floor of the office would slowly descend.
The entire process was completed through mechanical means.
No electrical current.
No software.
No electronic traces of any kind.
Lucian silently examined the structure in his mind.
He finally understood why this place had remained hidden for so many years.
Electronic devices left records.
Network systems could be traced.
Access control permissions could be bypassed.
But with a traditional mechanical mechanism like this, as long as the owner kept the key in their possession, outsiders would have virtually no way to open it through normal means.
Whoever had designed it had not pursued complexity.
Instead, they had chosen the most reliable method.
The simpler the mechanism, the harder it was to leave traces.
Lucian slowly withdrew the Azure.
The pale blue mist gathered once more.
The night wind swept across the rooftop again.
In the distance, the manager's office remained illuminated.
The entire commercial office building continued to maintain its usual tranquility.
Nobody knew that, just moments ago, the greatest secret hidden within the building had been completely unraveled.
Lucian gazed silently at the light on the sixth floor.
His expression remained unchanged.
He now knew where the hidden space was.
He also knew that its sole entrance was concealed behind the filing cabinet at the innermost end of the manager's office.
He had even mastered the mechanism's entire operating principle.
The remaining question was no longer whether he could get inside.
It was—
When should he enter?
He chose not to act immediately.
After all, a key was not the only way to operate the mechanism.
Others needed a key.
He had the Azure.
As long as he could directly access the interior of the lock cylinder and analyze the position of every locking plate, the Azure could replace the key and reproduce the same mechanical movements.
The entrance was no longer an obstacle.
What he needed to consider now was how to deal with whatever awaited him inside the hidden space.