"When Xu Wen was recalling the incidents related to Song Mu, she mentioned something. At that time, you may have gone to the neighbor's old lady for help."

After saying that, Liang Zichen gave an awkward laugh and said, "Captain Wang, why bring up these old stories?"

"When Xu Wen recalled, she mentioned that once she went to Han Mo's house, wanting to find out about Han Mo's feelings for Song Mu, but she saw a disgusting scene. Han Mo was entangled with a man at the time, and that man had a large scar on his back."

"Ah! You mean Han Lin and Han Mo are having an affair?" Liang Zichen asked in surprise after hearing Wang Shen's words.

"At least that's my guess for now. But Han Lin has always denied any relationship with Han Mo, and even pretends not to know her. And his explanation for the scar on his back is that he was scratched by a poorly installed window sill during renovations." Wang Shen smiled, probably mocking the clumsy excuse Han Lin made up.

"Is there a problem here?" Liang Zichen looked at Wang Shen with a blank expression.

"Looks like you didn't do well in physics in high school either," Wang Shen shook his head helplessly. "Let's assume his reasoning is correct. Do you think a small piece of glass could cause such a large scar?"

Liang Zichen thought for a moment, then shook his head.

“Yes, a small piece of glass couldn’t have caused such a large scar. If it was a glass scratch, it would have to be a large piece of glass. We’ve determined the size of the glass, and then we’ll analyze its location. If it had only hit Han Lin’s back, would it have caused such a large scar?” Wang Shen paused again and asked Liang Zichen.

Liang Zichen thought for a moment, then shook his head.

"So how do you think it would be possible to create such a large scar on a piece of glass?"

"If it were to cause such a large scar, then it would probably only be..." Liang Zichen said, pondering the possibilities. "If it were to cause such a large scar, it would only be from falling from a height, landing squarely on the back, and creating a large wound." Liang Zichen snapped his fingers and said.

“That’s right, but that would create another problem. I’ve observed his back, and there are two suspicious points. First, the scar on his back is very neat, unlike one cut from glass. Second, and most importantly, apart from that scar, there are no other scars on his back.” Wang Shen glanced at Qi Huan’s position again as he spoke.

"What do you mean? I don't understand." After Wang Shen finished speaking, Liang Zichen shook his head.

"Sigh." Wang Shen sighed and explained, "You just said that only a very large piece of glass could cause such a big scar. And Han Lin said it was the glass from his own renovation, so it must be intact. Besides, you also said that such a large piece of glass would have to fall from a height and hit your back to cause such a big scar. So, think about it again, wouldn't such a large piece of glass shatter if it fell from a height?" Wang Shen looked at Liang Zichen, constantly guiding him to come up with his deductions.

"Yes," Liang Zichen nodded affirmatively. "Ah! I understand," Liang Zichen snapped his fingers again.

“If a large piece of glass hits someone on the back, it should shatter into many pieces, so there would definitely be more than one scar. But you just said that Han Lin’s back has no scars other than that big one, which creates a contradiction.” Liang Zichen stated his judgment, and perhaps feeling that his deduction was reasonable, he couldn’t help but smile.

"Hmm, you're teachable. However, you've overlooked a few details of daily life." Wang Shen also gave Liang Zichen a satisfied smile.

"Huh? Is there something I haven't noticed?"

"Let me ask you a question. If you were renovating your home, you would definitely need to install windows and use glass. What kind of glass would you choose?" Wang Shen suddenly changed the subject and talked about home renovation, which left Liang Zichen somewhat puzzled.

"Glass? Captain Wang, you've stumped me. I really don't know what the difference is between different types of glass. Aren't all glass transparent?" Liang Zichen looked at Wang Shen with a puzzled expression.

Wang Shen glanced at Liang Zichen, sighed heavily, and then said helplessly, "Glass can be roughly divided into two types: tempered and non-tempered. You must know that, right?"

After listening to Wang Shen's words, Liang Zichen nodded. "I know a little about that; it's said that tempered glass is safer."

Do you know why tempered glass is safer?

Hearing this question, Liang Zichen looked at Wang Shen blankly again and shook his head. "Captain Wang, we're talking about Han Lin's scar on his back, why are we bringing up the glass issue?"

"We are simply refuting Han Lin's reasoning. Tempered glass, when shattered, forms shards with almost no sharp edges. Untempered glass, on the other hand, will have sharp edges when shattered, which is very dangerous. Even tempered glass isn't expensive these days. So, if you were renovating your home, would you use tempered or untempered glass?"

"Then of course we'll choose the tempered glass one." Liang Zichen had just finished saying this when he suddenly realized something and slapped his forehead.

“I understand,” Liang Zichen said. “Han Lin isn’t short of money, so he’ll definitely choose tempered glass for his home renovation. If it’s tempered glass, it’s virtually impossible for such a large wound to occur, and there won’t be such a big scar.”

“That’s right.” Wang Shen confirmed Liang Zichen’s idea. “So, Han Lin is lying!”

"But why would he lie?" Liang Zichen asked.

"There's only one explanation: this scar carries a secret we can't know. Our next task is to uncover that secret to the best of our ability." Just as Wang Sheng finished speaking, he received a text message on his phone: "Captain Wang, the key has been copied and is on your desk."

After reading the text message, Wang Shen walked over to Xu Xiaolin. He quietly asked her, "Can you handle things here?"

After listening to Wang Shen's words, Xu Xiaolin gave an OK sign. Wang Shen nodded, patted Liang Zichen, and the two left the hospital building.

"Captain Wang, where are we going now?" Liang Zichen asked Wang Shen, sitting in the passenger seat, with a puzzled look in his eyes.

"Take a look at this message." Wang Shen tossed his phone to Liang Zichen.

"The key has been copied, so what's next?" Liang Zichen glanced at the text message and asked, still looking puzzled.

"Then, of course, we'll try to see which door this key opens." With that, Wang Shen stepped on the gas, and the car sped off towards the police station.

"Oh my god, my weekend is ruined," Liang Zichen sighed, leaning back in the passenger seat.