"Half of a key?"
Standing under the light, something in Lin Wu's eyes sharpened at once.
Not fear.
The opposite.
It was the kind of brightness that only appeared when truly valuable information finally surfaced—so valuable that even breathing seemed to tighten around it.
She tapped the counter once.
"Go on."
"If you can't explain it clearly, I'm not taking this order."
Professor Zhou Qiming sucked in two heavy breaths in the rain, as if the breath holding him up until now was finally about to break.
He didn't waste another word.
Instead, he pushed the girl beside him half a step forward.
"Shen Xiaohe. She comes in with me."
Lin Wu raised a hand and authorized entry.
"Zhou Qiming. Shen Xiaohe. Entry approved."
A flash of gold.
The two of them stepped over the threshold at once.
The girl was clearly at her limit. Her legs nearly gave out the moment she crossed inside. She almost collapsed outright, but Qi Ye caught her by the arm on instinct. The second his palm touched her wrist, he felt a chill sink into his skin.
Not fever-hot.
The opposite.
Cold all the way through.
Shen Xiaohe looked up at him, lips pale, whispered, "Thank you," and then immediately locked her gaze back onto the dark silver companion chamber outside—as if terrified it might rupture in the next second.
Professor Zhou had no attention left for anything else.
The instant he entered, he looked first at the Special Goods Cabinet, then at the isolation bench, and only after that forced his gaze back onto Lin Wu.
"The thing you took in just now," he said hoarsely, "was Sample One."
"The one outside is Companion Chamber Two."
He swallowed.
"They were never supposed to be transported separately. And they absolutely were never supposed to destabilize in the same district."
Lin Wu didn't comment.
She only asked, calmly:
"What door are they supposed to open?"
This time, even Qin Zheng said nothing.
Because that question struck straight into the center of every piece of chaos tonight had revolved around.
Professor Zhou went quiet for two seconds, clearly calculating how far he could go.
But when he saw the gray mist behind the Special Goods Cabinet ripple again, the last of his hesitation scattered.
"It wasn't a virus project."
"At least… not entirely."
His voice dropped lower and lower as he spoke, as if he feared being overheard—or feared the sentence itself.
"Three months ago, Heng'an Biotech discovered the first interface reaction point in the western collapse zone. At first we thought it was underground mineral radiation, or some kind of abnormal magnetic field. Later we realized…"
His throat moved.
"It wasn't ore. It wasn't magnetism."
He looked straight at Lin Wu.
"The wall had gone thin."
At the shelves, Su Yu understood none of it.
But somehow that only made it worse.
Not understanding left a colder kind of dread crawling down her spine.
Lin Wu, however, understood half of it immediately.
Her gaze didn't move.
"What's behind the wall?"
Professor Zhou looked at her and answered, word by word:
"Other worlds."
The instant those four words landed, the store fell so silent it felt hollowed out.
Qi Ye, who had been leaning against the counter, slowly straightened all the way up.
Pei Wan's eyes darkened slightly too.
Even Qin Zheng's cold, controlled expression cracked—just a little—for the first time.
Only Lin Wu remained behind the counter without the slightest sign of disorder.
Because more than anyone else in the room, she already knew that other worlds were real.
Her store door had opened onto one last night.
Professor Zhou, of course, didn't know that.
He took her composure for incomprehension—assumed she hadn't yet grasped the full weight of what he was saying.
So he continued.
"Sample One isn't a complete sample. It's more like a guide beacon."
"It amplifies. Calls. Attracts. It strengthens the interface reaction."
"Companion Chamber Two isn't just a container either. It's more like an anchoring unit."
"It stabilizes coordinates. Keeps the opening from sealing shut immediately."
He drew a breath that sounded like it hurt.
"Separately, they're both dangerous."
"Together…"
His voice roughened completely.
"They look for a door."
Shen Xiaohe spoke then, her voice quiet but shaking hard.
"To be accurate…"
"…they look for something that can bear the door."
One of Lin Wu's brows lifted slightly.
She remembered the system's earlier prompt instantly.
Light resonance detected between Special Goods Cabinet and store owner status.
Which meant it wasn't just the two objects searching for a door.
Inside her store, they had already found something that matched.
Qin Zheng finally spoke, voice hard and cold.
"Professor. The last time you got a resonance reading from the other side—what did you see?"
Professor Zhou's face drained.
The question seemed to drag him back into some memory so bad it still had teeth.
He closed his eyes.
Only after several seconds did he answer in a low voice.
"Snow."
"Ruins."
"And an entire skyline of burned black high-rise skeletons."
Qi Ye's fingers tightened abruptly.
The movement was brief.
But Lin Wu caught it.
Which told her enough.
Professor Zhou was not describing an abstract vision.
He was describing Qi Ye's world.
Or at the very least, a region overlapping heavily with the wasteland plane Qi Ye had come from.
At that point, the final line in Lin Wu's mind clicked into place.
Her supermarket was not randomly connected to infinite worlds.
At least not yet.
The first door that had opened was not random at all.
Heng'an Biotech had already started prying at that thin wall—
and her store had become the thing that stabilized the breach first.
"So the infected?" Pei Wan asked suddenly. "What do they have to do with the wall thinning?"
Professor Zhou's expression worsened again.
"Interface reactions aren't pure energy."
"They carry contamination. Residual activity. Things that don't belong on our side."
"If a human is exposed, mild cases look like neural collapse, high fever, a spike in aggression."
He swallowed.
"Severe cases end in direct structural breakdown."
Then he looked at all of them.
"The infected you see outside right now…"
His voice dropped until it sounded like sand dragged across metal.
"In a sense, they're the result of the first failed contact."
Su Yu's face went white instantly. She clutched Sui Sui even tighter without realizing it.
Until this point, she had still been telling herself it was a virus.
And now this old man was telling her the things outside hunting people down might not be just infection at all.
They were fallout.
Residue from something leaking through the wall.
At that exact moment, Lin Wu finally asked the single most valuable question so far.
"Then why can my store suppress it?"
This time, Professor Zhou didn't answer immediately.
He looked at Lin Wu.
Then at the black Special Goods Cabinet behind her.
And slowly, the shock in his eyes changed into something more complicated. Something almost dazed.
"Because this place is no longer an ordinary building."
"Not just a thinning wall. Not just a crack opening."
His throat tightened. He had to stop for two seconds before forcing the rest out.
"It has already become…"
"…an anchor point."
Behind the gray mist, the Special Goods Cabinet rippled softly.
As if it recognized the word.
Qin Zheng's eyes darkened sharply.
"Professor. Are you certain?"
Professor Zhou kept staring at the cabinet.
"I wish more than you do that I weren't."
"But if Sample One entered this place and stopped spreading—if it was directly contained here—then there is only one explanation."
He looked at Lin Wu.
"It found the keyhole."
Silence.
The kind where every breath became audible.
Lin Wu stood beneath the lights, unmoving.
But in her mind, four words landed with absolute clarity.
Her store was the keyhole.
Not just a safe zone.
Not just a supermarket.
Something capable of actually bearing an interface gate.
Professor Zhou looked at her, his voice raw and heavy.
"The thing in your store isn't the key itself."
"The companion chamber outside isn't the key either."
"They only become a key when joined together."
He raised one hand slowly and pointed at the brightly lit little shop beneath Lin Wu's feet.
"But the thing that decides where the door opens…"
"…is this place."
At the exact instant those words landed, the system interface in front of Lin Wu began refreshing wildly.
[Keyword parsing complete: Interface Gate, Anchor Point, Keyhole.][Store core cognition update in progress.][Notice: Current store has been designated a "Growth-Type Interface Anchor."][Prerequisites for new feature fulfilled.]
A flash lit in Lin Wu's eyes.
She barely had time to process it.
Outside, the dark silver companion chamber suddenly emitted a soft beep.
It was faint.
But every face changed at once.
The blue ring-lights around the isolation bench lit in a circle, as if they had sensed something automatically. Behind the cracked observation window in the center of the chamber, the pale blue liquid—until now perfectly still—shifted once.
Just once.
As if something inside had moved in its sleep.
Shen Xiaohe went white.
"Professor…"
Her voice shook.
"It's waking up."