Han Xiaomei sneaked into the forensic science department, looking around cautiously, and finally seized the opportunity to sneak in.

A few minutes later, she carried a shoulder bag, nonchalantly slipped her hands into her coat pockets, limping in high heels, and confidently walked out of the city public security bureau.

The clock was approaching midnight when Yan Yin, who had been sitting silently in the living room, suddenly looked up. The next second, the doorbell rang.

“Scared me to death! When I was leaving, I bumped into Director Gou working overtime. He asked me why I went to the forensic science department in the middle of the night. I had to say that I forgot to register the evidence collection kit I brought from the scene yesterday and came to register it secretly when no one was around!” Han Xiaomei took out several bottles and spray bottles one by one from her bag, almost in tears, and said helplessly, “Director Gou even scolded me a few words. What if he tells Captain Yu? Will my bright career be tainted from the very beginning?”

Yan Yin remained silent, went to the kitchen to get half a cup of distilled water, and put on forensic gloves. He mixed the luminol and potassium hydroxide powders with water and poured them into the spray bottle filled with hydrogen peroxide.

“Yan Ge, what on earth are you doing?” Han Xiaomei finally realized, feeling scared, and asked softly, “Are you… cutting your wrist and splattering blood on the floor?”

“…”

Yan Yin looked her up and down, walked to the bathroom door, and took a deep breath.

Han Xiaomei followed quietly behind. She saw Yan Yin spraying the floor, corners, and washbasin multiple times with the spray bottle, and then he stepped out of the bathroom and turned off the lights.

“Hoo…” Han Xiaomei covered her mouth.

The washbasin in the darkness had faint sparkling dots, and a faint bluish-green luminescence slowly appeared on the floor. It was a reaction to bloodstains!

“Do you know what this is about?” Yan Yin asked.

“I-I-I didn’t see anything. I don’t know anything!” Han Xiaomei covered her eyes with her hands. “Team Yan, Brother Yan, Mr. Yan! I beg you, I promise I won’t say anything after I leave!”

“You should have learned it from your police academy textbook. Luminol solution is catalyzed by iron ions in blood, resulting in blue luminescence. Therefore, it is used to detect bloodstains at crime scenes. But if there are other strong oxidants present at the scene, luminol will also luminesce. So, the use of hypochlorite bleach or feces and urine at the scene will interfere with forensic investigators’ judgment of bloodstains.”

“We memorized it,” Han Xiaomei stuttered, “Hypochlorite catalyzes strong fluorescence that lights up very quickly, while the fluorescence catalyzed by iron ions in blood lights up slowly. It can be distinguished by taking photos with long exposures…”

“But what about when surveillance cameras were not common back then?” Yan Yin asked in return.

Han Xiaomei’s mind was spinning desperately, but the intimidating presence of Deputy Chief Yan made her thoughts stumble.

“It’s actually simple,” Yan Yin revealed a cold smile and said slowly, “As long as the scene is sealed and kept dry, the oxidants will evaporate after a few days, but the iron ions will not disappear for a long time. Even after several years, luminol will still light up.”

“Oh…” Han Xiaomei whispered.

“I was away for three weeks. No matter how much bleach was used, it should have evaporated completely in a completely dry environment. So, the fluorescence we see now is not from hypochlorite, but from blood.”

The fluorescence was very faint. On one hand, it was because it had been cleaned with bleach, and on the other hand, the amount of blood was not large, and it had been diluted by water, causing the bloodstains to spread extensively. Han Xiaomei’s mind was in a mess, and she subconsciously asked, “Whose blood is it?”

As soon as the words came out, she wished she could bite her own tongue off.

“Who else could it be?” Yan Yin looked at the fluorescence patterns on the floor and countertop, his voice filled with gloom. “Of course, it’s that bastard surnamed Lü.”

Han Xiaomei: “…”

In the evening, a red flag car stopped at the entrance of the residential building. Director Lü got out of the car and politely declined the driver’s offer to carry his bag upstairs. He walked alone, unsteadily, into the entrance of the building.

Then he turned a corner, immediately straightened his back and lifted his head. He walked lightly, with agile steps, into the elevator.

“I’m back!” Director Lü opened the door amidst the sound of keys rattling, loudly announcing his arrival. He placed his bag under the coat rack in the foyer and then took off his shoes. The sound of his wife stir-frying vegetables came from the kitchen. He turned around, relaxed his shoulders, and then froze in mid-air.

Yan Yin sat in the middle of the living room sofa, expressionless, looking at him.

“You see this child, he just came and brought something.” His wife came out of the kitchen with a plate of glossy and delicious braised pork with mushrooms and eggs, smiling and chattering, “It’s not New Year’s or any special occasion. What does he bring skincare products for an old lady like me? I told him, where do I even apply that? This old face is already a mess, it would be a waste even if I use it…”

His wife happily returned to the stove to cook scrambled eggs with golden needle mushrooms, leaving only Director Lü and Yan Yin facing each other in the spacious room.

“When Jiang Ting visited Yue Guangping without permission, only half a year later, Yue Guangping died, and Jiang Ting’s life was ruined.” Director Lü finally sighed and muttered, “The country should really establish a regulation prohibiting deputy directors from casually visiting the homes of police chiefs. This omen is truly ominous…”

Thud! A glass filled with rock sugar chrysanthemum and wolfberry tea was placed on the desk by Director Lü. He then sat in the swivel chair with a grunt and asked while putting on reading glasses, “What exactly do you want? Let me remind you, you are currently suspended and under investigation. You are not allowed to inquire about any daily affairs or case-related information at the city bureau. Any violations will be treated as disciplinary offenses.”

“On that evening when you came to my house, what were you planning with Jiang Ting?” Director Lü’s hand paused. “What… What?”

Yan Yin remained expressionless.

“…,” Director Lü picked up the tea cup. “I’ve told you everything I should. There’s no point in asking about what I can’t tell you. I’m not like Old Wei, you can’t soften me up with a few coquettish words. Rules are rules…”

Smack! Yan Yin pulled out a portable hard drive from the inner pocket of his coat and slammed it on the desk.

Director Lü almost choked on his tea. “What is this?”

“It’s the surveillance footage from the back door of the Hupin residential area on the night you were stabbed by Jiang Ting.”

The study suddenly fell silent for a moment, and both of them focused their gaze on the small, unremarkable silver portable hard drive on the desk, unsure of what they were contemplating. After several minutes, Director Lü finally said slowly, “The surveillance footage has been taken and sealed at the city bureau. According to confidentiality regulations, the property management company is not allowed to restore and disclose the original video to anyone unrelated to the case. Otherwise, they will bear serious criminal responsibility…”

“But internal company leaders can access it.” Yan Yin interrupted him and said, “Sorry, but my father has become the new CEO of that property management company.”

Director Lü: “…”

A difficult-to-describe expression finally appeared on Director Lü’s usually chubby, smiling face. From his mouth shape, the phrase he forcibly held back should be, “Damn you!”

“On that night three weeks ago, when you visited my house to meet Jiang Ting, you proposed an undercover operation. Unlike the rumors you spread later, Jiang Ting didn’t refuse you. He agreed.” Yan Yin leaned back in his chair, his eyes beneath his arched eyebrows emitting a cold light.

“You planned for Jiang Ting to stab you, and then escape from Jianning overnight. But there was a very dangerous point. It would take Jiang Ting at least several hours to reach a place where the police couldn’t find him immediately. Even if the wound you received avoided major blood vessels and organs, it would be difficult to hold on for a few hours in the cold, rainy night without rescue—so you planned for a time gap.” Director Lü leaned on his forehead, remaining silent.

“Jiang Ting did leave his home at around nine o’clock, but you stayed in my house until early morning. I estimate that you only stood in my bathroom and carefully aimed the knife at yourself after the street cleaners started working. You made a shallow cut. You used to be a forensic expert, handling hundreds of bodies over the years, so you knew the human body’s structure and blood vessel distribution like the back of your hand. The reason you didn’t stab yourself outside was that it rained until the next morning, and the ‘scene of the crime’ you had surveyed in advance was very dark and secluded. If the visibility was low and you accidentally stabbed yourself off target, it could have resulted in a genuine accident.”

“After tidying up the bathroom, you left my house and went to the scene of the crime. You punctured the small blood bag that had been prepared in advance, and it was naturally discovered by the sanitation workers and sent to the hospital.” Yan Yin calmly said, “A self-inflicted stab wound is different from being stabbed by someone else. If a careful examination is conducted, it would be discovered. But Director Hu from the Technical Support Brigade of the Provincial Public Security Department, who is responsible for injury assessment, is Master Gou Li’s mentor from our city bureau. As long as there is a prior hint, he won’t go to great lengths to come and conduct a thorough examination.”

Director Lü wanted to refute, but Yan Yin didn’t give him the chance. “In addition to that, there is another piece of evidence that can be used—surveillance footage from the residential area. However, the video is not clear. When I was being monitored by Fang Zhenghong a few months ago, he was discovered one evening while following me downstairs. Afterwards, Jiang Ting and I jointly tampered with the video from the property management company. It was at that time that Jiang Ting remembered all the blind spots in the surveillance within the residential area.”

Director Lü pressed down on his throbbing forehead and said earnestly, “Yan Yin, I understand that you are unwilling to believe that Jiang Ting is a traitor. But can you occasionally, reluctantly, deign to believe in your superior?”

“Superior?” Yan Yin’s eyes flickered with a mocking smile. “Vice Director Wei and Deputy Chief Yu have known about your plan from the beginning, right? Otherwise, if the small blood bag that burst open at the ‘crime scene’ were tested for chloride penetration, it would have exposed the truth.”

Director Lü: “…”

Director Lü finally sighed deeply. “Yan Yin, Director Yan, Deputy Chief Yan,” he helplessly asked, “Why can’t you believe that it was Jiang Ting who stabbed you at my house, then took advantage of the chaos to escape, while I lied about being attacked outside in order to protect you, this damn embryo?!” “Because it was you who used bleach to clean the blood stains in the bathroom,” Yan Yin coldly replied, “Jiang Ting wouldn’t mistake my face towel for a rag.”

Director Lü, an experienced old fox, probably couldn’t have imagined that the final flaw would come from this. He silently sat in the large swivel chair, his round face, which had only just recovered in a few days, drooping. Only his eyelids twitched uncontrollably, unable to be stopped.

“Do you have anything else to say?”

“…Yes.”

Yan Yin made a mocking gesture without a hint of amusement.

Director Lü couldn’t hold back any longer and finally asked, “You, a man in his thirties, why the hell are you using an old yellow towel to wash your face?!”

Yan Yin raised the corner of his lips without any amusement, “An old towel has good water absorption. Otherwise, how could the smell of chlorine last until now?”

The two of them locked eyes for a long time. Director Lü had a complicated expression, unsure whether he should praise Yan Yin’s exceptional investigative awareness or regret that he ultimately stumbled upon an old towel. On that night, he didn’t use his own coat to wipe away the remaining bleach, fearing that the wool fabric fibers would be left in the ceramic tile joints, leaving suspicious traces. But unexpectedly, his cleverness backfired, and it became the workings of fate.

“Getting old, getting old!” After a stalemate for several minutes, Director Lü shook his head and sighed heavily, “Useless, sigh!”

Leaning against the chair back with his legs crossed and hands clasped in front of his chest, Yan Yin asked with a hint of mockery, “So, Jiang Ting didn’t actually stab you?”

“…,” Director Lü nodded.

“And he didn’t voluntarily join the Black Spade K?”

Helpless, Director Lü nodded again.

It seemed that something was choking Yan Yin’s throat, making it hard for him to speak, his gaze fixed on the figure before him.

“According to the plan, Jiang Ting infiltrated the drug trafficking gang of Wu Tun and Wen Shao, intending to dismantle the entire underground drug trafficking route from the China-Myanmar border to Jianning. This matter is highly confidential, known to only a few individuals and has obtained the approval of Director Liu from the Provincial Public Security Department. We have promised Jiang Ting that if he successfully completes the mission, he will be vindicated and the truth about the 1009 explosion case from three years ago will be revealed to the world.”

“If Director Lü hadn’t come to my door, I could have maintained the charade with you for a while longer…”

“Do you still believe in me? If you don’t, it’s for the best.”

“…When we meet again in the future, we will be mortal enemies, and death is the best filter…”

“Yan Yin,” the vast expanse of sky and sea reflected in Jiang Ting’s eyes as he gazed fixedly at the figure of his beloved, “I love you.”

Countless sounds reverberated in their eardrums simultaneously. Yan Yin lowered his head, covering his mouth and gasping for breath. Overwhelming joy and extreme pain tore through his chest, twisting his liver and intestines, wrenching out an excruciating agony of suffocation.

Director Lü crossed his hands, his fingers interlocked, and lowered his head slightly. Sharp glints shot out from the gap in his reading glasses:

“You should be proud of Jiang Ting, Yan Yin. He has already transmitted the first very important piece of intelligence to us.”