He saw a small, hexagonal room, lighted by a single wall candle. At the square table in the center a man sat reading a document roll. He only saw his broad back and hunched shoulders.

As the judge tiptoed inside with Tao Gan on his heels the man suddenly looked round. It was Guildmaster Wang.

Wang jumped up and threw his chair backward against Judge Dee's legs. When the judge had scrambled up Wang had run around the table and drawn a long sword. As Judge Dee looked at his face distorted with rage something whizzed past his shoulder. Wang ducked with a quickness amazing in so ponderous a man. The knife landed with a thud in the door of the cupboard against the back wall.

Judge Dee grabbed the heavy marble paperweight from the table. Turning half-aside to avoid the sword thrust that Wang was aiming at his breast, he overturned the table with a powerful push. Wang had quickly retreated a step, but the edge of the table struck his knees. He toppled forward, but at the same time thrust his sword at the judge. As the sharp blade cut through Judge Dee's sleeve he crashed the paperweight on the back of Wang's head. He fell over the tilted table, blood oozing from his crushed skull.

"My knife just missed him!" Tao Gan said ruefully.

"Sht!" Judge Dee hissed. "There may be others about!"

He stooped and examined Wang's head. "That paperweight was heavier than I thought," he remarked. "The man is dead."

When he righted himself his eye fell on two high stacks of black leather boxes that were piled up against the wall on either side of the door. There were more than two dozen of them, each provided with a copper padlock and a carrying strap.

"That's the kind of box our ancestors used for storing gold bars!" the judge remarked, astonished. "But all seem to be empty." He quickly surveyed the room and continued: "Han Yung-han knows that one lies best if one mixes his lies with the largest possible quantum of truth. When he told me the tale about his alleged abduction, he described these secret headquarters of the White Lotus under his own house! Han must be the leader; he sent Liu Fei-po away to transmit his last instructions to the local heads of the conspiracy. Also, Wang must have held a high position in the society. His head is bleeding heavily, Tao Gan! Wipe the blood up with your neckcloth, then wind it tightly round his head. Presently we shall hide his dead body; we mustn't leave any traces of our visit here!"

He picked up the document roll Wang had been engrossed in. He held it near the candle; it was covered with small, neat handwriting.

Tao Gan wiped the blood from the table and the paperweight, then wrapped the cloth round the dead man's head and deposited the body on the floor. As he was righting the table, Judge Dee said excitedly:

"This is the complete plan for the rebellion of the White Lotus! But unfortunately, all the names of persons and places are written in code characters! There must be a key to this. Look in that cabinet against the back wall over there!"

Tao Gan pulled his knife from the door and looked into the cabinet. On the lower shelf stood a row of large seal stones, all engraved with slogans of the White Lotus. He took the small document box of carved sandalwood from the upper shelf and handed it to the judge. It was empty, but there was place for two small document rolls. Judge Dee rolled up the document he had picked up from the floor. The outside of the protecting flap consisted of purple brocade. The roll fitted exactly into the box; next to it there was just enough space for a second roll of the same size.

"We must find that second roll!" Judge Dee said in an agitated voice. "That must contain the key! See whether there is a secret wall safe!"

While he himself lifted the carpet and scrutinized the stone floor, Tao Gan pulled the half-decayed wall hangings aside and examined the walls.

"Nothing but solid rock!" he reported. "Up there are a few apertures; I feel air coming through."

"Those are ventilation shafts," the judge said impatiently. "They'll come out somewhere on the roof of the house. Let's inspect the leather boxes!"

They shook every one of them, but all were empty.

"Now we go on to the other tunnel!" the judge said. Tao Gan took up his lantern, and they stepped out into the crypt. Pointing at a square hole in the floor by the side of the dark archway, Tao Gan remarked:

"That'll be a well!"

Judge Dee gave it a casual look. He nodded and said:

"Yes, Hermit Han thought of everything! This crypt was evidently meant as a hiding place for his family in times of trouble. Here they had his entire treasure of gold, dried rice to eat and water to drink. Give me a light!"

Tao Gan held the lantern high so that its light shone through the archway.

"This second tunnel must have been made much later, Your Honor!" he remarked. "The rock stops here, the tunnel has earthen walls, and the wooden shorings look quite new!"

Judge Dee took the lantern from Tao Gan's hand and let its light fall on an oblong, narrow box on the floor of the tunnel, close to the wall. "Open that box!" he ordered.

Tao Gan squatted and inserted his knife under the lid. When he raised it he quickly averted his face. A nauseating smell rose from the box. Judge Dee pulled his neckcloth up over his mouth and nose. He saw the decaying corpse of a man stretched out in the box. The head had been reduced to a grinning skull; frightened insects crawled over the tattered robe that clung to the rotting carcass.

"Put the lid back!" he said curtly. "In due time we shall examine this corpse. We have no time for that now!"

He went down ten steps. About twenty yards farther on he found his progress barred by a high and narrow iron door. He turned the knob and pushed it open. He looked out into a moonlit garden. Right in front of him he saw an arbor, overgrown with ivy.

"That's Liu Fei-po's garden!" Tao Gan whispered behind him. He poked his head round the corner and went on: "The outside of this door is covered with fragments of rock, luted onto its surface. The door forms part of a large artificial rock. In that arbor over there Liu was wont to take his siesta."

"This secret door explains Liu's vanishing tricks!" Judge Dee remarked. "Let's go back!"

But Tao Gan seemed reluctant to go. He looked at the door with undisguised admiration. They heard in the distance the shouts of the men who were trying to extinguish the fire in the Han mansion.

"Close that door!" Judge Dee whispered.

"Superior workmanship!" Tao Gan said regretfully as he pulled the door close. When he followed the judge back through the tunnel the light of his lantern fell on a recess in the wall. He grabbed the judge's sleeve and pointed silently at the dry bones in the recess. There were four skulls, which the judge examined. He said:

"The White Lotus apparently killed its victims in the crypt. These bones must have lain here for some time already. The body in the box was their most recent victim."

He quickly went up the flight of steps, entered the hexagonal room and said:

"Help me to get Wang's body to the well!"

They carried the limp corpse into the crypt, and dropped it into the dark hole. Far below they heard a splash.

Judge Dee again entered the room, blew out the candle and pulled the door to behind him. They crossed the crypt and climbed the steep stairs to the altar tunnel. When they were standing in the chapel again, the jade panel closed noiselessly.

Standing in front of it, Tao Gan depressed at random a few words of the inscription. But as soon as he had pressed down one square, and started on a second, the first rose and resumed its position level with the surface.

"What a fine craftsman that Hermit Han was!" Tao Gan sighed. "If one doesn't know the key sentence, one can press down these squares till one's hair goes gray!"