Some people drive luxury cars and live in villas at a young age, while others, also at a young age, have already begun to experience being extorted by them.

Poor Shen Zhengning, in the prime of his youth, hadn't even started a family or a career, yet was forced to experience a mid-life crisis of supporting the old and young, carrying a mortgage, and facing the impending unemployment of a programmer. Although Zhuang Mingqi, with nothing better to do at home, would coax him into driving the McLaren to work, compared to being "a kept man who keeps another pretty boy," he would rather choose the persona of a corporate drone crushed by the pressures of life and career.

Actually, for someone like Zhuang Mingqi, who wasn't short on money and had a pet to take care of, hiring a live-in housekeeper would have been a very suitable solution. But he was exceptionally picky in this regard. After trying out several candidates, he finally settled on one. As it turned out, less than three days later, the person tried to introduce their daughter to him and was promptly kicked out.

Now, only a part-time cleaner came to clean every other day. One man and one dog depended entirely on Zhuang Mingqi's cooking skills to survive. He truly practiced the saying, "as long as I have a bite to eat, so will you," and managed to feed the entire family into malnutrition.

Shen Zhengning, seeing the job through to the end, not only pulled him out of danger in the nick of time but also single-handedly took on the task of caring for him. He was like a household guardian beast, silently and invisibly soothing the chaos and fear brought about by this sudden incident. Both man and dog obediently revolved around him, adapting to the temporary life order that had been established.

Zhuang Mingqi had mostly recovered, but after the ordeal, he was still a bit weak and lacking in energy, relying on goji berries steeped in his thermos cup every day to keep going. He had been frequenting the third-floor living room recently. This room had excellent lighting; a bit too sunny in the summer, but perfectly warm in the winter. The first to discover this spot was Shen Zhengning, who needed to work overtime. But half an hour after he sat down, another person sprouted on the sofa next to him, and ten minutes later, a fluffy Dandelion sprouted at his feet.

Zhuang Mingqi was nestled in a corner that he had arranged little by little, like an ant moving house, pondering over design drawings. On the other side, Shen Zhengning wore glasses and typed on his keyboard, the main theme being a sense of companionship without disturbance. Silver was spinning in circles with Zhuang Mingqi's slipper in its mouth. After playing for a while, it got bored, looked left and right, and fixed its eyes on Shen Zhengning's laptop bag on the low table. It sneakily crept over from behind the sofa, pawed at it forcefully a couple of times, bit a corner of the laptop bag that was sticking out, and gave its head a dashing toss—

Clatter!

The bag, held upside down, spilled its contents all over the floor. The two focused men were startled and snapped back to reality at the same time. Zhuang Mingqi called out in a warning tone, "Silver!"

Silver stared with wide, innocent eyes. Hearing its master's call, it immediately and gleefully dashed towards him with its "prey" in its mouth.

"...You're done for." Zhuang Mingqi patted the dog's butt, his expression convincingly stern, but his voice betrayed a trace of unconcealed schadenfreude. "Don't drag me into this. Go on, give it back, quickly!"

"Even if you're done for, it won't be. Is that how you talk to your lifesaver?" Shen Zhengning calmly put down his laptop, his skill at taking sides having clearly reached a state of perfection. "The kid's just curious, don't scare it." He bent down to pick up the things on the floor, and suddenly let out a questioning nasal sound, "Hm?"

"What's wrong?" Zhuang Mingqi's attention was caught before he could get angry. He poked his head out from the other side of the sofa and saw a flat box, about the size of half a book, in Shen Zhengning's hand. "Postcards?"

"Yes." Shen Zhengning stood up with the box of postcards and flipped it over to look. "And it's a souvenir that Ye Tongsheng brought back from the United Kingdom. I just casually put it in my laptop bag at the time and completely forgot about it."

"From Ye Tongsheng? Let's open it and see." Zhuang Mingqi found his slippers from the other end of the room and came to his side. "They're ordinary scenic postcards. London Tower Bridge, Buckingham Palace... Wait, what's this one?"

Shen Zhengning pulled out a single postcard that was a size smaller and a layer thinner than the others. It was tucked inside a box of twelve uniformly sized postcards. If one didn't specifically take them out to look through one by one, its presence would have almost gone unnoticed.

The back of the postcard was printed with a bouquet of hand-drawn pink roses in a rather classical style. On the front, the postcode box in the top left corner read "201420", while the bottom right corner read "SW1A 2AH". There was no stamp, nor was any address written.

"Could it be a handwritten postcard that Ye Tongsheng was preparing to send, and it got mixed up with the gift by accident?" Zhuang Mingqi asked.

"This postcard is clearly not part of the same set as the others. It might have been custom-printed on Taobao in China." Shen Zhengning's gaze sharpened. "The number of postcards in the set isn't short, so there's no possibility that he took one to use and then replaced it with a non-matching one. Besides, since it was a gift he planned to give to someone, there would have been no need to open it beforehand, causing a postcard he intended to mail to get mixed in with the gift."

"The most likely possibility is that he did it on purpose—deliberately hiding a prepared postcard in a box of ordinary postcards. The souvenir was just a front; these two lines of text are the real message he wanted to convey."

"Wait, hold on!" Zhuang Mingqi had to interrupt him. "Forget about the secret code for a moment, how could you tell it's a custom-printed postcard from Taobao?"

"The six-box postal code field in the top left corner is a format defaulted to only by postcards in our country." Shen Zhengning casually pulled out a local UK postcard to show him. "Other countries don't print them like this. Also, this postcard has no barcode, no manufacturer's logo, and no extra text. It doesn't look like a cultural and creative product sold individually or as a set, which is why I said it's most likely custom-ordered from a design on Taobao."

Zhuang Mingqi was convinced. He said with sudden realization, "Ye Tongsheng custom-ordered a postcard, personally left a secret code, and found a way to give it to you, hoping you could decipher the hidden information. And then you just casually put it aside and forgot all about it in the blink of an eye, for a whole two months..."

"Ahem... an oversight." Shen Zhengning gave a guilty cough. "But then again, there was almost a week between when he gave me the postcard and when he passed away. If Ye Tongsheng wanted me to notice this code as soon as possible, shouldn't he have dropped a hint? But he didn't say anything. I'm more inclined to believe he was just using me as a backup."

"But weren't you two not close? Why would he give this secret code to a colleague he didn't know well?"

"I'm curious too, but unless he comes back to life to explain it himself, we probably have no way of knowing." Shen Zhengning said, "Let's not worry about his intentions for now. The key is the secret code on this postcard."

Against the backdrop of Zhuang Mingqi's aggrieved "Weren't you the one who brought it up first?", Shen Zhengning opened a search page and typed in a string of numbers. "201420... is it a postal code? Hmm, codes starting with 20 are for Shanghai City, 201400 is for Fengxian District, but there's no such postal code as 201420."

"201420 could also refer to the 20th named storm of the 2014 Pacific typhoon season—Typhoon Nuri." Shen Zhengning stroked his chin thoughtfully. "Does it refer to the word 'Nuri'?"

"Why don't we put this aside for now and look at the line below?" Zhuang Mingqi pointed to "SW1A 2AH" in the bottom right corner. "I don't know why, but I feel like it looks a little familiar."

Shen Zhengning typed "SW1A2AH" and hit enter. The search page returned a pile of ads that looked like gibberish. "Looks like it's not a fixed code... which means the combination of characters must have some meaning."

But with a code that had no hints, thinking divergently would present too many possibilities, no different from searching for a needle in a haystack. Shen Zhengning was lost in his own thoughts. Zhuang Mingqi, not giving up, turned the laptop screen towards himself and scrolled back two pages, but still couldn't find any useful information. He sulkily rubbed Silver's head and muttered to himself, "No, I've definitely seen it somewhere before."

Shen Zhengning stared at the card in a daze, then suddenly said, "There's so much blank space on the card face. Why did Ye Tongsheng specifically write this line of code in the bottom right corner? Logically, this spot should be used for the postcode... Wait, should there be a space here?"

A lightbulb seemed to go "ding" above Zhuang Mingqi's head. "That's right!" He quickly reached out and typed a space between the "A" and the "2", then hit enter with a "smack". "This is a UK postcode. Because it's not obvious in handwriting, UK postcodes need a space before the last three characters—Got it! This is... uh, the British Foreign Office?"

The screen prominently displayed the official website of the British Foreign Office. In the mailing address section, it read—

Foreign, Commonwealth & Development Office

King Charles Street

London SW1A 2AH

"Since this postcode corresponds to the British Foreign Office, does the 201420 in the postcode box also correspond to a location? Could it be not in this country?" Shen Zhengning took out his phone, opened Taobao, and used its image search function on the pattern on the back of the card. "And this rose... he didn't use a commercially available postcard, but chose to have it custom-made, so this picture must have a meaning."

The almighty Taobao searched and found a pile of floral illustrations and decorative paintings, all for 9.9 yuan with free shipping. Shen Zhengning glanced over them roughly and felt none of them matched. Zhuang Mingqi leaned over to take a look. "I actually know this variety of rose. It's a Moss Rose. Look, its stem and the outer layer of the bud have a lot of moss-like fuzz. It's also called Mossy Rose. Because its flowers are beautiful and fragrant, it's always been very popular in Europe. You can often see it on medieval porcelain and in oil paintings."

Shen Zhengning leaned forward and searched for "Moss Rose". "First appeared in 1696, popular during the Victorian era..." He leaned back into the sofa. Zhuang Mingqi subconsciously held his breath, afraid of disturbing his train of thought. "Both clues point to the United Kingdom. So if we divide 201420 into three sets of numbers, they correspond to the English letters 'T', 'N', 'T'. Is it dynamite? I seem to remember there's also an international courier with that name."

Zhuang Mingqi retorted, "Could it be that he buried TNT downstairs at someone's place, as a tribute to The Great Detective Sherlock Holmes and Detective Sherlock?"

Various permutations spun in his mind like a kaleidoscope. Hearing the keyword, Shen Zhengning suddenly paused subtly. "That quote you mentioned last time, Ye Tongsheng said it to you, right?"

"Wha... Oh, you mean that famous Sherlock Holmes quote. Yes, he said it." Zhuang Mingqi answered, completely puzzled. "What's wrong?"

Shen Zhengning shot up from the sofa. "Ye Tongsheng likes Sherlock Holmes! He mentioned it to me himself, so that's the clue! You've said it several times too, but I just let it go in one ear and out the other! My god, I should really find some spicy crayfish seasoning and stir-fry myself right now."

Zhuang Mingqi was startled by him. "Well, that's not really necessary..."

Shen Zhengning grabbed the laptop, typed a few characters, and turned the screen to Zhuang Mingqi, his eyes shining astonishingly. "Since he's familiar enough with the original Sherlock Holmes stories to quote them offhand, how could he not use that line of thinking when creating a secret code?"

"TNT—The Naval Treaty."

"A Foreign Office clerk is ordered to copy a naval treaty. While he's away from his office, the document is stolen, so he asks Sherlock Holmes for help in recovering the treaty."

Zhuang Mingqi scanned the first half of the story, taking in ten lines at a glance. "Hmm, Foreign Office clerk, King Charles Street... that does match up. But what does the pattern on the back mean? Does the rose have a special meaning?"

"It's Holmes's 'discourse on the rose'." Shen Zhengning scrolled the article to the middle. "Everything humans do is first for the sake of survival, but the color and fragrance of a rose are an embellishment of life, not a necessary condition for its survival. 'Only benevolence can produce these extraordinary qualities... Humanity places great hope in flowers.'"

"Now we have the title, the beginning, and the golden quote, so the solution to the riddle is obvious: 'an important document that has been hidden'." Shen Zhengning explained in a rapid-fire manner while quickly sending a WeChat message to a contact. "Following the original plot of the story, the document was stolen by the Foreign Office clerk's fiancée's brother and hidden under the bedroom floorboards. But because the clerk fell ill and occupied his bedroom, the culprit never had a chance to retrieve the document. I remember Ye Tongsheng was renting his place, which also happens to correspond. If he lived in that house, no one else could... Okay, I have the address. I'll make a trip over."

"Wait," Zhuang Mingqi leaped to his feet. "I'm coming with you!"

"...Dress warmly!"