"The magistrate himself," Tang answered promptly. As the judge lifted his eyebrows he explained quickly, "He was an enthusiastic devotee of the tea cult, your honor, and most particular about all its details. He always insisted on fetching the water himself from the well in his garden, and he also boiled it himself on the tea stove in his library. His teapot, cups and caddy are all valuable antiques. He kept them locked away in the cupboard under the tea stove. On my instructions the coroner also made experiments with the tea leaves found in the caddy, but those proved to be quite harmless."

"What measures did you take thereafter?" Judge Dee asked.

"I at once sent a special messenger to the prefect in Pien-foo, and I had the body placed in a temporary coffin, put up in the hall of the magistrate's private residence. Then I sealed the library. On the third day his excellency the court investigator arrived from the capital. He ordered the commander of the fort to place six secret agents of the military police at his disposal, and instituted a thorough investigation. He interrogated all the servants and he-"

"I know," Judge Dee said impatiently. "I read his report. It was clearly established that no one could have tampered with the tea, and that no one entered the library after the magistrate had retired there. When did the investigator leave exactly?"

"On the morning of the fourth day," Tang replied slowly, "the investigator summoned me and ordered me to have the coffin removed to the White Cloud Temple outside the east gate, pending the decision of the deceased's brother as to the final burying place. Then he sent the agents back to the fort, told me that he was taking all the magistrate's private papers along with him and departed." Tang looked uncomfortable. Glancing anxiously at the judge, he added, "I presume that he explained to your honor the reason for his sudden departure?"

"He said," Judge Dee improvised quickly, "that the investigation had reached a stage where it could profitably be continued by the new magistrate."

Tang seemed relieved. He asked, "I trust his excellency is in good health?"

"He has already departed for the south, on a new assignment," the judge replied. Rising, he continued. "I'll now go and have a look at the library. While I am gone you'll discuss with Sergeant Hoong what matters must be dealt with during the session tomorrow morning."

The judge took up one of the candlesticks and left. The door of the magistrate's residence, located on the other side of a small garden behind the reception hall, was standing ajar. The rain had stopped, but a mist was hanging among the trees and over the cleverly arranged flower beds. Judge Dee pushed the door open and entered the deserted house.

He knew from the floor plan attached to the reports that the library was located at the end of the main corridor, which he found without difficulty, Walking through it he noticed two side passages, but in the limited light circle of his candle he could not see where they led to. Suddenly he halted in his steps. The light of the candle fell on a thin man who had just come out of the passage directly ahead, nearly colliding with him.

The man stood very still; he fixed the judge with a queer, vacant stare. His rather regular face was disfigured by a birthmark on his left cheek, as large as a copper coin. The judge saw to his amazement that he wore na cap; his graying hair was done up in a topknot. He saw vaguely that the man was clad in a gray house robe with a black sash.

As Judge Dee opened his mouth to ask who he was, the man suddenly stepped noiselessly back into the dark passage. The judge quickly raised the candle, but the sudden movement extinguished the flame. It was pitch dark.

"Hey there, come here!" Judge Dee shouted. Only the echo answered him. He waited a moment. There was only the deep silence of the empty house.

"The impudent rascal!" Judge Dee muttered angrily. Feeling along the wall, he found his way back to the garden, and quickly went back to the office.

Tang was showing Sergeant Hoong a bulky dossier.

"I want to have it understood once and for all," Judge Dee peevishly addressed Tang, "that none of the personnel shall walk about in this tribunal in undress, not even at night and when off duty. Just now I came upon a fellow wearing only a house robe, and not even a cap on his head! And the insolent yokel didn't even bother to answer me when I challenged him. Go and get him. I'll give him a good talking to!"

Tang had started to tremble all over; he looked fixedly at the judge in abject fright. Judge Dee suddenly felt sorry for him; after all, the man had been doing his best. He went on in a calmer voice. "Well, such slips will happen now and then. Who is the fellow anyway? The night watchman, I suppose?"

Tang shot a frightened look at the open door behind the judge. He stuttered, "Did… did he wear a gray robe?"

"He did," Judge Dee replied.

"And did he have a birthmark on his left cheek?"

"He had," the judge said curtly. "But stop fidgeting, man! Speak up, who is he?"

Tang bent his head. He replied in a toneless voice, "It was the dead magistrate, your honor."

Somewhere in the compound a door slammed shut with a resounding crash.

"WHAT door is that?" Judge Dee barked.

"I think maybe it's the front door of the private residence, your honor," Tang replied in a faltering voice. "It doesn't shut properly."

"Have it mended tomorrow!" the judge ordered brusquely. He remained standing there, in grim silence. Slowly caressing his side whiskers, he remembered the queer vacant stare of the apparition, and how quickly and noiselessly it had disappeared.

Then he walked round his desk and sat down in his armchair. Sergeant Hoong looked at him silently, his eyes wide with horror. With an effort judge Dee composed himself. He studied Tang's gray face for a moment, then asked, "Have you seen that apparition too?"

Tang nodded.

"Three days ago, your honor," he replied, "and in this very office. Late at night I came here to fetch a document I needed, and he was standing there, by the side of his desk, his back turned to me."

"What happened then?" the judge asked tensely.

"I uttered a cry, your honor, and let the candle drop. I ran outside and called the guards. When we came back, the room was empty." Tang passed his hand over his eyes, then added, "He looked exactly as we found him, your honor, that morning in his library. Then he was wearing his gray house robe with the black sash. His cap had dropped from his head when he fell on the floor… dead."

As Judge Dee and Sergeant Hoong remained silent, he went on. "I am convinced that the investigator must have seen him too, your honor! That is why he looked so ill that last morning, and why he left so abruptly."

The judge tugged at his mustache. After a while he said gravely, "It would be foolish to deny the existence of supernatural phenomena. We must never forget that our Master Confucius himself was very noncommittal when his disciples questioned him on those things. On the other hand, I am inclined to begin by seeking for a rational explanation."

Hoong slowly shook his head.

"There's none, your honor," he remarked. "The only explanation is that the dead magistrate can't find rest because his murder is not yet avenged. His body is lying in the Buddhist temple, and they say that it is easy for a dead man to manifest himself to the living in the proximity of his corpse, and when decomposition has not yet advanced too far."

Judge Dee rose abruptly.