You Mingxu couldn’t answer this point. If it were some special underground space, perhaps the water quality and soil would differ from the surface. Given Yin Chen’s caution, washing away traces was possible.

“Should we arrange for someone to check with the Municipal Construction Department?” someone suggested.

Xu Mengshan looked at You Mingxu.

You Mingxu paused and said, “Wait.” She moved the mouse, pulling up yesterday’s surveillance footage of Yin Chen at the crime scene on the computer, then stopped at a particular frame.

It was the same image she had been pondering in the car on the way back.

“What do you think Yin Chen is doing?” she pointed at Yin Chen’s finger placed on his ear.

Almost everyone strained to focus on the image.

Yin Chen’s movement was so small and quick that if you weren’t looking carefully, you wouldn’t notice it at all. In other words, this was an unconscious gesture. Just like when a hair falls on your face and you feel itchy, you’ll brush it away. But you might not even be aware you’ve made this movement.

Now that You Mingxu had pointed it out, everyone noticed.

“His ear is uncomfortable,” Xu Mengshan said gravely.

You Mingxu nodded. Yes, his ear was certainly uncomfortable. But why?

One police officer said, “Otitis media?”

Another officer explained seriously, “Otitis media causes continuous discomfort, not such a sudden reaction. It doesn’t look like that.”

“Itchy?”

“He didn’t scratch it; he rubbed it several times.”

“Water in his ear?”

“Where would water get in his ear?”

“Wouldn’t you tap your ear if water got in? Rubbing would push it deeper.”

…

You Mingxu listened to everyone’s brainstorming, but she felt that none of their suggestions was right. She felt there was something strange about how Yin Chen looked.

Like a flash of light suddenly appearing in her mind, she hesitantly spoke up: “Do you think… could he be experiencing auditory hallucinations?”

Everyone was startled.

Xu Mengshan mulled over this word: “Auditory hallucinations… why?”

A strange intuition drove You Mingxu to continue: “What if the place where he’s been staying is very noisy? Continuously, incessantly noisy? Then his ears would become uncomfortable, and even after leaving that environment, he might occasionally experience auditory hallucinations. That would explain such an inconspicuous gesture, why he would unconsciously rub his ear to hear more clearly.”

Yes, that was the feeling. Yin Chen’s movement at that moment gave her the impression not of discomfort but of having heard something that startled him. That’s why it seemed unusual. Could there be some sound that accompanied him at several crime scenes? Something that made him uncomfortable?

You Mingxu continued, “The previous times we saw Yin Chen, he never made this small gesture. Is it possible that the new place he’s been staying recently has affected him?”

“A place that’s continuously noisy…” Someone followed Xu Mengshan’s earlier line of thought, “Could it be a basement near a railway or subway?”

Everyone’s spirits lifted, and another person added, “So could the traces on his car and shoe soles be engine oil or railway gravel, which is why he was afraid of being discovered? And the smell—could it be from a sewer?”

Everyone seemed eager to pursue this theory, and even You Mingxu was moved. However, she still felt something wasn’t quite right.

A basement near the railway? It seemed close to the answer, but still somewhat forced. Would the noise from trains passing by occasionally be strong enough to cause such obvious auditory hallucinations? Would the stench from sewers clinging to his body be noticeable enough for even the car wash attendant to smell? Would traces from around a station be so obvious that Yin Chen had to thoroughly clean them off?

Fine beads of sweat formed on You Mingxu’s palms. By now, water might still be filling that warehouse, perhaps already reaching the chests of those five people. This meant they essentially had only one chance to concentrate all their forces in this direction—if they were wrong…

“Are there any other possibilities?” You Mingxu spoke up. “This answer still feels problematic to me. It seems like each condition being met requires just the right coincidence. Unique traces that must be washed away, the smell, a continuously noisy environment…” She vaguely felt that something was about to reveal itself.

“A farmhouse?”

“A pig farm?”

Two voices spoke simultaneously.

It was You Mingxu and another police officer. You Mingxu had spoken purely from intuition. Her heart jolted, and she looked at her colleague, who showed a slightly embarrassed expression and said, “I’m from a rural area. What you described perfectly fits the pig farms in my hometown—the stench, the ground covered in feces and bran that you’d step in accidentally. And the pigs are always grunting; if you stay there for a few hours, your head starts spinning and your ears ring. And as for water pipes, exhaust fans, and empty pig pens like this—they’re very common.”

Once he said this, everyone had a moment of realization. Thinking it through, each person couldn’t help but get excited—indeed, just as You Mingxu had said, for a basement near a railway to meet all these conditions would require quite a coincidence. But a pig farm completely satisfied all these conditions!

Xu Mengshan excitedly slapped the table: “That’s exactly the kind of place! It has to be!”

All the detectives’ eyes gleamed like wolves’. How could they not be excited when, with just a few surveillance clips and a one-minute video, without any other specific clues, they had collectively reasoned out such a logical answer?

At this moment, people once again looked toward You Mingxu.

The ears, the smell, the car washing—all these key details had been discovered by her. When everyone was leaning toward the railway theory, she had maintained her clarity, not rushing or becoming impatient, not overlooking other possibilities. And while it wasn’t surprising that the colleague from the rural area thought of a pig farm, she had thought of it simultaneously. How could one not admire such keen perception, meticulousness, and intellectual power?

“Sister You is truly Sister You,” someone sighed.

“But…” someone said, “Even if we know it might be a farmhouse, there are many farmhouses in Xiangcheng, even more in the suburbs. We don’t have much time left—how do we find it?”

Everyone looked at You Mingxu.

She frowned in thought, but after a moment, her brow smoothed, and she said, “No, it’s very easy to find.”

Everyone was taken aback.

Xu Mengshan also seemed thoughtful, glancing at the frozen image of the warehouse on the screen, murmuring, “Yes, he has concerns…”

You Mingxu smiled in understanding and said, “That’s right. Look, Yin Chen has been living there these past few days without worrying about revealing his whereabouts. He had to bring five hostages back, lock them in a warehouse, flood it, leave to send a video—so many things in such a short time… He must ensure absolute control over this place, ensuring he won’t be discovered, and no one will accidentally enter and find the hostages and call the police. So, this can’t be a large farm; he couldn’t control a large farm alone. He’s been wanted for several days now, with intensive police forces everywhere looking for him, yet he hasn’t been found. So he wouldn’t be wandering around trying his luck, or someone would have reported his whereabouts by now. This small farm is likely somewhere he’s been before and is very familiar with, perhaps even having some kind of connection to him. And there were probably very few people originally guarding the farm, allowing him to easily take control of it.”

This reasoning was both ingenious and convincing. Everyone nodded in agreement.