A After lunch, the three of them returned to the garden. Toan carried a small oil lamp from the dining hall. Anh brought a clean sheet of paper and two pencils. Minh said nothing on the way — he walked quickly, his eyes already thinking. Inside the library, Toan lit the lamp. The room changed completely. In the warm orange light, it did not feel frightening or cold. It felt like a room that had been waiting for someone to come back.

B The walls were covered in maps. Anh looked at them carefully. The lines showed mountains, rivers, and paths — but the writing beside them was in letters he had never seen before. Some books on the shelves had the same strange letters on their covers. Others had no writing at all. Toan was already on the floor, looking behind the lowest shelf. His long arm disappeared into the corner. “There is something here,” he said. He pulled out a small wooden box covered in dust. Inside, wrapped in cloth, were three sticks of chalk and a folded piece of paper. Minh unfolded it carefully. Someone had written one sentence in plain, clear letters: “The answer is always in the room.”

C Minh was already moving along the middle shelf, reading each spine carefully. Anh looked at Toan. “What is a spine?” he asked quietly. “Is it like a spider?” Toan laughed — a short, surprised laugh. “No, no. The spine is the side of the book — the part that faces you when it sits on the shelf. It usually has the title on it.” He showed Anh the nearest book. Anh nodded slowly. Then Minh stopped. He pulled out a thin book with three small carved rings around its spine. The rings did not move. The book would not open. “A puzzle lock,” said Toan. “Each ring is a number. Find the right three numbers — in the right order — and it opens.”

D They searched the room. The first number was above the door — a small symbol carved into the stone above the frame. The second was scratched into the underside of the reading desk. The third was on the folded paper from the box, written so small that none of them had noticed it at first. Minh knew the symbols — he had studied them years ago. He read them as four, one, seven. Anh set the rings carefully: four — one — seven. A soft click.

E The book opened. Inside were pages covered in short, careful handwriting. Each entry had a day number at the top. Anh read the first few lines. “It is like a diary,” he said. “Someone wrote in it every day.” Toan nodded. “A journal,” he said simply. “Same thing.” They read the entries together in the light of the lamp.

F Nobody spoke for a long time. Day 181 had nothing — just a small ink mark, as if the writer had started to write and then stopped. Toan looked at the mark for a long moment. “Someone was here,” he said quietly. “And then they were not.” Minh copied the last two entries onto his sheet of paper, very carefully. Then he closed the book, set the rings back to their original position, and placed it back on the shelf exactly where he had found it. They left the library in silence, covering the door with the plants as before. Outside, the afternoon sun was still warm. It felt strange — to step back into a normal day after reading something like that.