Kuang Feifan was startled when Xu Hui told him he had a birthmark on his back, instinctively twisting his neck to look, only to realize he couldn't see it. He frantically searched for a mirror while asking, "What birthmark? When did I get a birthmark?"

Xu Hui followed him to the wardrobe, pulling the door open to reveal a full-length mirror. In the reflection, Kuang Feifan finally saw it: nestled below his right shoulder blade, slightly off-center, was a vivid, crimson handprint. At first glance, it certainly resembled a birthmark, but Kuang Feifan knew he had none, and the size of the print immediately brought the 'Big-Headed Monster Infant' to mind.

Kuang Feifan bent his arm to touch it; there was no sensation—no pain, no itch. Because craning his neck to view his back was an awkward position, he gave up after a moment, trying to dismiss it. "This probably isn't a birthmark. Maybe I was hit in the small building and got a bruise. It doesn't hurt anyway."

Xu Hui hadn't intended to closely inspect Kuang Feifan’s back, but he still said with a touch of concern, "You should let your girlfriend take a look, just in case there's some underlying ailment."

"Pah..." Kuang Feifan was thoroughly displeased by the word 'ailment' leaving Xu Hui's mouth, yet Xu Hui had a point. If there was an injury, it was best for Bai Ru to examine it, especially since this wasn't a superficial scratch or abrasion. Who knew if it carried the 'Corpse Poison' they had discussed?

Kuang Feifan hastily dressed, and the two left the master bedroom on the second floor, heading downstairs to the guest room. They knocked, and Bai Ru had just finished showering, now clad in a set of clean men's clothes.

Seeing Kuang Feifan and Xu Hui rush toward her in such a flurry, Bai Ru wondered what had happened and quickly asked, "What is it?"

Xu Hui nudged Kuang Feifan with his elbow, signaling for him to speak. Kuang Feifan, who had been secretly admiring the beauty who had just emerged from her bath, quickly started unbuttoning his shirt as he was jostled. "I think I hurt my back."

Bai Ru paused, then her face darkened when she saw the sudden 'birthmark' on Kuang Feifan’s back. She turned to Xu Hui and commanded, "Take off your shirt too. I need to check your back."

Xu Hui jumped. "I'm fine! I didn't feel anything..."

Kuang Feifan noticed Bai Ru's grave expression and cut Xu Hui off. "Just take it off. There might be a problem."

Reluctantly, Xu Hui removed his shirt. Bai Ru and Kuang Feifan both stared, their expressions registering shock. On his back, just below the shoulder blade, slightly toward the center, was a stark, hand-shaped red mark. It truly resembled a birthmark, yet it was entirely crimson with clearly defined edges, absolutely incapable of being a simple bruise. The redness was unnerving to behold.

Kuang Feifan realized his back was likely in the same condition as Xu Hui's, and his heart tightened. He asked Bai Ru, "What... what is this?"

The thought of the sudden red handprint appearing on both his and Xu Hui’s backs felt like a stone lodged in Kuang Feifan’s chest.

Xu Hui now understood that his back also bore the handprint, and his face instantly fell. Both men turned to Bai Ru, hoping she had a way to remove the marks.

To their dismay, Bai Ru’s expression was intensely serious. After a long silence, she finally spoke, "This thing... there’s no way to remove it quickly, unless..."

She stopped speaking.

"Unless what?" Kuang Feifan pressed urgently.

Bai Ru sighed softly. "Unless we can completely resolve the malevolent spirit in the small building."

"What do you mean?" Kuang Feifan and Xu Hui were confused.

Bai Ru gestured for them to redress, then explained, "The handprint that appeared on you has a name: the 'Soul-Lock Mark.' It must have been placed on you by that Vengeful Infant, or perhaps pressed directly onto your souls. While the mark itself won't cause direct physical harm, it greatly affects your souls, and critically, it locks onto your auras. This means no matter where you are, you can be found at any moment. Essentially, you’ve been tagged."

"Found at any time? GPS?" Xu Hui blurted out.

Bai Ru nodded. "It’s similar to that."

Kuang Feifan frowned deeply. "Is that all? Just to tag us?"

Bai Ru hesitated, then resolved to tell them the rest. "This mark also possesses the ability to attract Yin spirits."

Neither man spoke; they just stared wide-eyed at Bai Ru.

Bai Ru gave a wry smile. "It means you might see ghosts anytime, anywhere..."

That entire night, Kuang Feifan, Xu Hui, and Bai Ru were virtually sleepless. The final conclusion of their discussion was that the 'Soul-Lock Mark' could not be eliminated by human effort; only by destroying the entity that cast the mark could the crimson scar be removed. In other words, they had to eliminate the strange infant in the small building to succeed.

However, based on the experiences Kuang Feifan and Xu Hui recounted, Bai Ru could tell the malevolent spirit in the building would not be easily vanquished. Clearly, the lingering vengeful spirits were not limited to just the Big-Headed Monster Infant, though they couldn't yet determine the exact number.

It wasn't until they were in bed that Xu Hui suddenly remembered the small notebook they found in the small building. He hastily got out of bed, retrieved the clothes he had changed out of, and fumbled in the pocket for the little book.

After some thought, he took the notebook and found Kuang Feifan, who insisted on sleeping on the living room sofa. He pulled him out of his covers and explained about the notebook.

The two studied it for a long time but couldn't uncover any valuable clues. Finally, Kuang Feifan suggested taking it to the appraisal center to see if they could decipher the smeared writing. Moreover, the first few pages of the notebook seemed to have been torn out; there were faint impressions on the initial blank pages, but lacking the right tools and fearing they might destroy the subtle marks, Kuang Feifan dared not attempt anything.

Xu Hui agreed that was the only way forward. After chatting a bit longer, Xu Hui suddenly said, "I'm sorry. I got you into this. If I hadn't insisted on going to the small building for clues, you wouldn't have the 'Soul-Lock Mark.'"

Kuang Feifan managed a weak smile. "Forget it, it’s no big deal. There's no immediate life threat. The worst-case scenario is just seeing more ghosts, and we aren't exactly strangers to that."

Xu Hui tried to say more, but Kuang Feifan waved his hand. "No need for apologies. Actually, going into the small building wasn't entirely fruitless. At least we know He Shaoqing is inside. Next, we figure out how to rescue him first."

Upon hearing He Shaoqing’s name, Xu Hui nodded vigorously.

They barely managed a short sleep, staying up nearly until dawn. Kuang Feifan immediately headed for the appraisal center with the notebook. Xu Hui, nursing a terrible headache, went to the precinct to request leave. Bai Ru remained at the villa, contacting Gu Yi to first inquire about any developments on his end, and then updating him on their situation.

When Gu Yi heard about the appearance of the 'Soul-Lock Mark,' he too found the matter quite thorny, though fortunately, he was already on his way back to the city.

After hearing Bai Ru's report, Gu Yi confirmed the address of the small building and told her, "I'll handle this myself. You don't need to tell them. I'll go in and check the situation. If things get too difficult, the priority is still getting He Shaoqing out."

Bai Ru asked with worry, "You're going alone..."

Gu Yi smiled. "Don't worry. I can't guarantee clearing out the evil spirits in that building, but finding one person shouldn't be a problem."

Bai Ru disagreed. "I'm coming too. If you aren't out by midnight, I’m going in."

"Uh..." Gu Yi recognized the firmness in her tone and couldn't object, so he agreed.

The journey back to the city was smooth. Gu Yi arrived outside the small building just past 2 PM.

He stood outside the courtyard gate, observing. Through his discerning sight, the entire building within the yard was shrouded in a layer of dull, ashen mist, a sight that caused Gu Yi himself to inwardly startle.