A Reply That Could Never Be Sent

Night fell.

The convoy did not stop at any guesthouse, but drove straight into the heavily guarded military airfield in the western suburbs.

A military transport plane stood quietly on the apron, ready to depart. Its enormous propellers resembled silent steel beasts in the darkness.

Holding Nuannuan, Su Mingfeng was the first to board.

The soldiers of the guard company and Su Mingzhe followed close behind.

Inside the spacious cabin, Su Mingzhe finally had a table where he could work without worry.

He switched on the high-powered flashlight he had brought and once again laid the letter bearing the words "Green Pine" on the table.

The shocking turn of events that day made him even more certain that deeper secrets must still be hidden in this letter.

He put on white gloves and, using a pair of precision tweezers, carefully tried to separate the glued edges of the envelope.

The damp had made the envelope's paper fragile; even a little force could tear it apart.

His movements were more delicate than embroidery.

Nuannuan had recovered from the fright she had suffered that day.

She sat beside her uncle without making a fuss, holding her heart-shaped stone in her arms and quietly watching her third uncle work.

She knew her third uncle was doing something very, very important.

He was helping Mommy catch the bad guys.

She wanted to help too.

But she did not know what she could do.

She picked up a pencil from the table and found a clean sheet of white paper.

Leaning over the table, she imitated her third uncle's serious manner and began scribbling and drawing on the paper.

She could not write, nor could she draw complicated pictures.

She could only draw the simplest things.

First, she drew a tree, a very, very tall tree.

Then, after thinking for a moment, she drew a great big axe against its trunk.

The axe chopped through the trunk.

The big tree fell with a boom.

When she finished, she held up her "masterpiece" and handed it to Su Mingzhe, saying softly, "Third Uncle, look. I'm helping you catch the 'bad pine tree.'"

In her simple world, "Green Pine" was a pine tree that had gone bad.

As long as it was chopped down, all the bad guys would be caught.

Su Mingzhe was fully absorbed in separating the envelope when a drawing suddenly appeared before him. Hearing his niece's innocent words, he could not help relaxing his taut nerves.

He set down the tweezers and took the drawing.

The lines were crooked and the proportions entirely wrong, yet to him, it was the most precious work of art in the world.

He smiled, a smile from the heart.

He stroked Nuannuan's head, his voice infinitely gentle. "Thank you, Nuannuan. You're wonderful."

He paused, looking into Nuannuan's big, crystal-clear eyes, and decided to explain the significance of this in a way she could understand.

"Nuannuan, do you know? This letter is actually the last puzzle your mommy left for the country."

"Mommy?" Nuannuan's eyes brightened.

"Yes." Su Mingzhe's gaze grew distant and sad. "Before Mommy left us, she discovered some very, very bad people. She didn't have time to tell us, so she hid the secret in this letter. Now, only you can help your uncles solve this puzzle and catch all those bad guys."

"Only then will Mommy be at peace up in heaven."

Nuannuan nodded, only half understanding.

But she understood the most important part-only she could help her uncles solve it.

A feeling she had never experienced before, the feeling of being needed, welled up in her heart.

She no longer felt like a burden who only caused trouble.

She felt useful.

"Third Uncle, I'll definitely help you!" She nodded hard, her little face filled with solemn resolve.

Su Mingzhe smiled and murmured his agreement, then returned his attention to his work.

Perhaps Nuannuan's words had encouraged him; this time, his hands were exceptionally steady.

Finally, after spending nearly half an hour, he successfully separated the envelope's hidden layer intact.

The hidden layer was empty.

There was nothing inside.

Su Mingzhe frowned.

Had he guessed wrong?

He refused to believe it.

Holding the inside of the envelope up to the powerful flashlight, he examined it carefully, inch by inch.

Suddenly, his gaze froze.

On the inside of the envelope, near the flap, he discovered a row of extremely tiny raised dots that almost blended into the paper!

It was Braille!

Su Mingzhe's heart began pounding uncontrollably.

He immediately found paper and a pen, then translated and recorded the Braille code one symbol at a time.

His fingers trembled slightly with excitement.

Little sister, just what did you leave behind?

Su Mingfeng came over as well and stood behind him, watching him write strange symbols on the paper.

Soon, all the Braille code had been translated.

But it was a meaningless string of letters.

"Z G Z J..."

Su Mingzhe stared at the string of gibberish, lost in thought.

It was encrypted.

A codebook was needed to decipher it.

But where was the codebook?

His gaze unconsciously fell on the letter again.

The letter, the mineral vein map, the diary...

Wait!

The diary!

A flash of lightning seemed to streak through Su Mingzhe's mind!

He suddenly remembered that the tin box found in Li Family Village had contained not only the mineral vein map, but also his younger sister's diary!

Could that diary be the codebook?

Once the thought arose, he could no longer suppress it.

He immediately turned toward Su Mingfeng. "Brother! Our sister's diary! Quickly!"

Su Mingfeng understood at once too. He immediately opened the classified document case he carried and took out the diary with its yellowed cover.

Su Mingzhe took the diary, both hands trembling.

He opened it and quickly scanned page after page.

His sister's diary entries were sporadic.

Most recorded her daily life during pregnancy and her hopes for the future.

Happiness filled every line.

Su Mingzhe held back his grief and kept turning the pages.

Finally, in the last few pages of the diary, he found something unusual.

The handwriting on those pages had become noticeably scrawled and hurried.

One page contained only a few isolated characters.

"Wind, rain, thunder, lightning, snow."

On another page was a strange table marked with numbers and Chinese character components and radicals.

This... this was a cipher she had devised herself!

Su Mingzhe worked in scientific research and had some knowledge of cryptography. With a single glance, he understood the principle behind it.

It was a double cipher based on dates and the structure of Chinese characters!

He immediately began deciphering the gibberish "Z G Z J" according to the rules provided in the diary.

Fine beads of sweat formed on his forehead.

Under his pen, Chinese characters slowly appeared on the paper, one after another.

The first character... "inside."

The second... "ghost."

The third... "in."

The fourth... "capital."

When the final character was written, Su Mingzhe and Su Mingfeng both sucked in a sharp breath.

It was as though all the air had been sucked out of the cabin at that moment.

Four characters were written clearly on the paper.

The mole was in the capital.