Xiao Cuo didn't betray any emotion as he lit a cigarette, slowly exhaled a smoke ring, then narrowed his small eyes and began his narrative.

"That night was special, much like tonight. A young detective, on duty at the Public Security Bureau, was sorting through the mail when he discovered an anonymous letter. Driven by curiosity, he opened it. The moment he did, his eyes were assaulted by shocking text—a confession written in blood. The writer remained nameless, but confessed to having recently killed someone on Shuǐyuán Mountain and disposing of the body down an unfathomably deep tree hollow. His sole purpose in writing was to ease his conscience before death. The letter stated he would commit suicide at the site of the murder to atone for his sins, and the time specified for the act was that very night!

Because the matter was of grave importance, the young detective immediately consulted his superior, who promptly dispatched the four on-duty detectives available at the time to Shuǐyuán Mountain to investigate and search. Back then, Shuǐyuán Mountain had not been developed; it was desolate, rarely visited by anyone.

It was past one in the morning when the four detectives reached the foot of Shuǐyuán Mountain, yet they resolved to press on into the wilderness to find the murderer who had confessed in writing and the tree hollow mentioned in the letter.

The older detective deduced that a tree hollow deep enough to be unfathomable could not be the work of an ordinary tree, thus narrowing their search radius to a few exceptionally large trees. After searching separately for over an hour, the young detective indeed found a bottomless hollow beneath a colossal, ancient camphor tree, though there were no signs of anyone having been there recently.

The four on-duty detectives gathered at the rim of the hollow, a faint, putrid smell wafting up from within. Some clinging vines partially obscured the opening, and the weak beam of their flashlights could not penetrate the darkness inside, as if the hole descended straight into the earth. They debated whether to enter. Young and fearless, the rookie patrolman immediately volunteered to descend and investigate. The others, reasoning that the worst they might find inside was a corpse, offered no objection.

The tree hollow's opening was small, but ample for the young detective to squeeze through. Before long, he was completely swallowed by the darkness. Even with the flashlight, his silhouette could no longer be seen from the outside; they could only listen quietly to the sound of him crawling forward, his clothes scraping against the wood of the inner walls.

What followed next threw the three detectives outside into chaos!

First, they heard a piercing, tragic scream echo from the hollow, immediately followed by the young detective shouting for help and the sound of him thrashing wildly inside the trunk.

The three outside shouted the young detective's name and prepared to enter the hollow. Just as they were about to venture in, they saw the young detective’s two feet inching backward, almost reaching the mouth of the hole. Two of the detectives exchanged a look and without hesitation stepped forward, each grabbing one of the young officer’s ankles and pulling back, intending to haul him out.

But the moment their hands gripped his ankles, the young detective became even more frantic, shaking his legs violently, desperate to break free.

Bang! Bang! Bang!

A volley of gunfire shattered the quiet mountain air. Before the veteran patrolman beside him could even react, he watched one of the men holding the young detective’s ankle stumble back a step and fall, clearly shot in the waist. The other detective managed to avoid a serious wound, only having his arm grazed by a bullet.

Now, no one dared to try and pull the young detective out, but the shooting inside the tree hollow continued. When the gunshots finally ceased, the young detective stopped struggling, his legs dangling limply at the opening of the hollow.

The old patrolman, having just tended to the wounded officer’s injury, saw that the young detective was motionless. He and the other uninjured officer then pulled the young man out. The young detective remained unconscious, his arms covered in gashes, his face crisscrossed with scratches, though mercifully he had not been shot.

Taking the two injured men and wary of whatever had attacked the young officer inside the hollow, the old patrolman decided it was best to return and call for reinforcements at daybreak to investigate further. That night, the two more seriously injured officers were rushed to the hospital; fortunately, their lives were not in danger. The young detective didn't wake from his unconscious state until the next morning. But when the old patrolman questioned him about what had happened in the tree hollow the previous night, the young detective began to tremble uncontrollably, talking nonsense, eventually clutching his head and bolting from the hospital room, screaming repeatedly, 'A ghost! Let go! Let go…'”

Xiao Cuo stopped speaking at this point.

“What? Was he traumatized?” I pressed immediately, hating nothing more than having a story cut off mid-way.

Xiao Cuo’s Adam's apple bobbed, and he told me three words: “He went mad…”

“Mad?” I found that hard to believe; he was a police officer, after all, and should have had no prior mental issues. “Scared mad?”

The cigarette in his hand had burned down. Xiao Cuo looked at me with an odd expression, not answering my question, but slowly saying, “Do you believe in ghosts?”

I was momentarily speechless, not because I couldn’t answer, but because of the look in Xiao Cuo’s eyes—a blend of helplessness and warning that completely contradicted his usual demeanor.

“I recall telling you I don’t believe in that sort of thing,” I maintained my stance firmly.

Xiao Cuo nodded thoughtfully and continued, “Later, a psychiatrist examined the young detective and confirmed he had suffered a mental breakdown due to extreme shock.”

“But what exactly did he encounter in that tree hollow?” My curiosity about the case had indeed been piqued, just as Xiao Cuo had predicted.

“Hear me out. That day, the old patrolman took more men up the mountain to investigate, intending to thoroughly examine that bizarre tree hollow, even going so far as to fell the ancient camphor tree. Daytime was certainly better for maneuvering and practical work. Soon, the vines around the hollow’s mouth were cleared. Despite the brighter daylight, the hollow remained profoundly dim, impossible to see the bottom of at a glance. Finally, they resorted to breaking down the entire hollow bit by bit until the passage was fully exposed to light. The stench of decay permeated the air, yet looking into the opened cavity revealed nothing but emptiness.

The bewildered old patrolman stepped forward to examine the spot and, beneath the wood chips and debris, discovered…”

“Discovered what?” Seeing Xiao Cuo pause again, I couldn't help blurting out, Is this damn guy deliberately building suspense?

“They found an arm—severed, blackened, and clearly having rotted for some time. The hand was splayed open, as if desperately grasping for something,” Xiao Cuo added.

“Just one severed arm?”

“Only one severed arm,” Xiao Cuo confirmed with certainty.

“How is that possible?” I still found it incredibly far-fetched that a single severed arm could scare a brave detective to that degree.

“There is no 'possible' or 'impossible'; it is fact. The old patrolman didn't believe it either, so they had the bottom of the hollow dug out completely, but found nothing more. And there’s something else you’d never guess,” Xiao Cuo continued, sounding even more profound and mysterious.

“What is it?” I was fully invested in this story now.

“Remember I mentioned the young detective was covered in cuts and scratches when they brought him out?” Xiao Cuo asked me.

“Of course, I remember. Didn't you imply those were from struggling inside the hollow?” I had made that assumption instantly when I heard it, finding no flaw in the logic at the time.

Xiao Cuo swallowed again, speaking with grave seriousness, “The old patrolman took the arm back for examination and discovered that beneath the fingernails, there was blood belonging to that young detective.”

“What!” I suddenly felt a rush of blood to my head. “You mean…”

Xiao Cuo nodded slowly at me, now certain that I had grasped his implication. For some reason, I didn't pursue that line of thought further; I suspected what transpired in that tree hollow was far more complicated than it seemed.

“You’re just making up some tall tale you dug up somewhere, kid,” I said, so startled by the outcome that I hadn't even considered that possibility, or perhaps I hadn't wanted to. I suspected Xiao Cuo was deliberately trying to trick me.

“I’m not making it up. This genuinely happened,” Xiao Cuo’s serious expression was unyielding.

“Then where did you learn about it?” In my view, judging the reliability of an account heavily depended on the source.

“I used to work in the archives department, though only as a clerk managing old files.”

I believed his first sentence, but for the second, I was more inclined to believe he was a mental patient than a clerk.

“Initially, I had no interest in those dusty files, but then management ordered all records digitized, forcing me to review and input them one by one. That’s how I stumbled upon the records for this case. You know I’m fascinated by this sort of thing, so I went to considerable trouble to track down the old patrolman from that time, which is how I know the case so clearly.” Though Xiao Cuo was flawed in appearance, his narrative was seamless, leaving me no discernible loophole to deny it.

“What about the man who wrote the blood confession? Was the blood on the letter tested?” I suddenly realized I had overlooked these two points and quickly asked before I forgot.

“Of course, it was tested. The analysis concluded that the DNA of the blood on the letter matched the DNA of the severed arm perfectly—they belonged to the same person. As for the man who wrote the confession, the old patrolman and his team searched for a long time but never found him,” Xiao Cuo supplied, now sounding rather unsettled himself by the events.

“How was this case eventually closed? If they never found the body, how could it be ruled a homicide?” I still had many unanswered questions.

“Though the body was never found, the incident caused quite a stir among the higher-ups. To prevent public panic, the case was officially sealed,” Xiao Cuo whispered. It made sense; if nothing could be resolved, that was the inevitable outcome.

“I can’t believe something like this could happen,” I muttered, completely subconsciously, only realizing after I spoke that I had implicitly accepted the case’s veracity.

If the case unfolded as Xiao Cuo described, I wasn't sure if it would shatter my understanding of the world.

I closed my eyes briefly, my mind swarming with strange notions, unable to immediately organize my thoughts. But suddenly, an idea flashed through my mind, causing me to snap my eyes open.

The grasping severed hand, the walking corpse—the two cases seemed linked by some unseen thread, or perhaps they shared a fundamental similarity!

I wondered if it was because I had been dwelling too much on the case at hand, or perhaps simply a lack of rest, that I kept connecting events around me to this investigation. Simultaneously, I felt the surrounding clues were too numerous and messy, too chaotic to form a coherent picture, as if someone were deliberately guiding me into one perplexing problem after another.

I wasn't entirely sure about this feeling, but I sensed it wasn't just my own wild speculation; perhaps when the time was right, all the riddles would suddenly be solved.

“Do you think this case has any connection to the one we are currently investigating?” As I mulled it over, I couldn't help voicing my thought. Xiao Cuo must have heard, but Zhang Jiewei, still driving, showed no reaction.

“Oh! After all that talking, all that effort, Brother Lei has finally understood!” Hearing me speak, Xiao Cuo immediately latched onto me.

“What do you think I understood?” I still didn't grasp what Xiao Cuo was trying to hint at. Did he share my suspicion?

“There are… specters at work in this world!” Xiao Cuo seemed to hesitate about something. His apprehension made me realize my idea differed from his.

“There are… people at work in this world!” I retorted dryly, perhaps trying to bolster my own courage. “I mean the similarities between these two cases. Haven't you noticed where these two cases overlap?”

Xiao Cuo rolled his eyes and replied with only two words: “No.”

“We’ll be in Jingfeng Road in half an hour.” Just as I was about to press Xiao Cuo further, Zhang Jiewei, who had been playing the role of the silent driver, suddenly interjected.

“Oh?” I looked out the car window. Indeed, without realizing it, we had entered the main urban area of Liutaíhé City.

The air inside the car felt stiflingly close. I rolled down the window, hoping to breathe the fresh air outside and enjoy the novelty of Liutaíhé City’s night.

Though it was late, the distant lights still illuminated a patch of the horizon—probably a place that never slept. My gaze remained fixed there, and I failed to notice our route drawing closer to a specific location, nor did I pay attention to the changing atmosphere around us.

It wasn't until the car suddenly stopped that I snapped back from my internal musings, only to be struck dumb by the sight before me!