The lights behind them suddenly went out, and the tide of darkness hid them like a vast curtain.

"Listen, what's that?" William whispered to the others. So the party felt for the wall in the dark and stuck to it, listening carefully. But nothing came of it.

"It's strange. Just now I clearly heard it." William scratched his head.

Suddenly there was a dark wind, and only William felt it. He paused in alarm, his hand involuntarily fumbling for the laser gun.

The party looked at him in surprise, and then at the front.

"There you are, boy." A deep voice sounded in his ear. His intuition told him that the speaker was far away, yet close at hand. So he looked around nervously.

"Get ready to die!" The voice sneered and went away. Then it was quiet again as if nothing had happened.

"Ah, are you all right?" Ranran kissed him on the cheek and asked him softly.

"Oh, nothing. I'll beat him."

"Him? Who?"

"You'll see." He went on feeling his way in silence.

After a hundred meters, Photon suddenly sensed something was wrong under his feet. "It's so smooth here," He whispered.

"This is a dirt road that I designed specifically for this place. The tires of that sports car don't fit here." Said the spider robot.

"Yeah!" Natalie felt delighted secretly, "I love dirt because I can run through it and smell it... Hee-hee!" The dirt did smell sweet.

It was not a short stretch, a full kilometer long. "We are now about three kilometers away from the lab." Said Black Ghost, spotting a random scrawl in the darkness.

Well-hidden from the surrounding darkness, and gradually getting used to it, their pace quickened a little.

"Wait a minute," The spider told the others to stop first. They saw him sprawled over another strange symbol, showing it to them in the dim light. "Their ground patrol robots go as far as this." He explained, "You need not doubt, and they won't change their patrol area. Now it's about two and a half kilometers."

"How did you measure that?" Whispered Photon.

"Thanks to the help of these two planes." The spider robot patted the nose-turret of Plane 1 and said, "They were doing reconnaissance at high altitude that night, so the robots on the ground couldn't see them. And when they saw all the robots coming back to the lab, they told me where they were. Correspondingly, I labeled it here."

"Oh!" Photon was suddenly enlightened.

Soon they were quiet again, for it seemed that they could hear the sound of a robot patrol -- the unmistakable tramp of feet. It was just sunrise, and the blue light of the mother star was pouring down, but the party in the tunnel didn't notice. They had forgotten time, forgotten rest, and walked eleven kilometers without fatigue, as if they had inexhaustible strength at their command.

"It looks like a big one," Said Natalie, leaning over the tunnel wall and listening.

"Yes, they put the most robots around and outside the room where the animals are trapped." Plane 2 whispered to her.

"Let's go on." Said the spider, leading the others on for another five hundred meters until they heard the voices of the robots above,

"Come on, come on!"

"Wait, Captain, I think there's something around here."

At this, William's heart beat wildly. In half a minute there were beads of sweat in his hair and his face was pale and trembling. Ranran, Photon and Natalie glared at the darkness. Black Ghost 1 and 2 also had their turrets pointed at the ceiling. The breathless figures, lost in the dark tunnel, stood stiffly on the spot.

At this critical moment, they heard this voice from above,

"Where are the things? You must have imagined it! Come on, go and see somewhere else!"

Then the sound of the same footstep began again and faded away.

"Oh, I'm scared!" William gasped as he stroked his chest when silence had returned.

"We must be careful. The further you go in, the density of their patrols will only go to increase." Plane 1 alerted the others as he advanced.

"But they would not expect us to come here, would they?" Ranran asked with a glimmer of hope.

"It's hard to say. So far, at least, the secret tunnel has not been exposed. But I think they may find it..." Stammered the spider robot.

"It's this pipe again." William felt a cylindrical object and thought.

The road went straight ahead after two high-speed bends. Before they knew it, the darkness was flooding in again, and the mystery that William had so often encountered was growing stronger.

He began to feel the darkness piercing his face like bullet after bullet at high speed. But soon the bullets disappeared.

Ranran asked softly, "Are you all right?"

"I shall be all right, Ranran. Don't worry." His voice was a little faint.

There was still a huge stone hanging in Ranran's heart. "William is in a bad way," She kept thinking, so much that she nearly fell over. Fortunately, William picked her up in time.

"@ # % &..." Ranran was almost standing firm when a faint sound suddenly penetrated her ears from the rear. She turned her head suddenly, but the sound fled.

"Am I really hearing voices?" She asked several people in succession, all of whom had heard the noise but could not tell what made it.

Ranran had to temporarily put aside this doubt and continue to hide in the secret tunnel, quietly to the destination.

There was a more intensive sound of footsteps overhead, and the party stopped. Fortunately, this time it didn't stop. Just a minute later, it was gone.

"Safe." William said to himself.

The road spiraled down and then another hairpin appeared. The spectacle of the sports car crashing here flashed through Natalie's mind, as well as the screeching of the brakes and the loud crash.

"You can't run faster than me." She said to herself.

Another patrol of robots arrived. Underground, they were uniquely positioned to be safe lurkers.

"The robots patrol the area about once an hour." The spider touched a graffito again and whispered.

As they went on, the sound of footsteps above grew denser. At one point the patrol suddenly stopped again as the robot crouched down and listened carefully to the ground. Underground lurkers held their breath and crept softly.

The robot shook its head and strode away again. The party then breathed a sigh of relief, continued to follow the secret tunnel and passed a high-speed bend turning left, quietly sneaking.

"Here is the gate to the laboratory, some distance from the room where the animals are trapped." Said the spider, pointing to the letter "G" on the wall. "My surprise is almost here. Pay special attention to this one below!" He said and pointed to the huge "No Loud Talking" sign below, "Because if we make too much noise, we may be arrested by the robots here!"

"OK!" They said more softly.

Walking along this section of the tunnel, they could hear the robots talking above them all the time. When two of the robots met, they were directly above the lurkers. So the spider signaled the others to stop.

After the voices were magnified by the solid walls of the tunnel, they heard,

"Hey, are you going to Room 51, Pork?"

"You guessed it, George. What's wrong; are you going to catch some animals?"

"Oh, no, it's just that I'm on my way with you. I'm going to the caretaker's lounge for a cup of coffee. You know, these last few days have been really boring and interesting. He didn't arrange many genetic tests, so we guards had nothing to do but drink and play cards in the lounge."

"Oh, really? He sets so little store by a gifted keeper like you?"

"Bingo! Suffice it to say, all I have demonstrated in the last few days is an exceptional ability to play cards. I earned $100(conversed)!"

"Wow, you're great! Let's go. In less than a month, all these valuable experimental materials will be dying for his great project!"

Amid a roar of laughter, they left.

"Damn it!" Said William indignantly.

"Looks like we'll have to do it sooner rather than later." Whispered Ranran.

They groped their way through the darkness for another five hundred meters or so until they found that the road ahead was narrowing. In the end, the planes were all blocked.

"You can't get through, comrades." Said the spider, pointing ahead, "Would you please retreat to a place wide enough to wait for us? I will take others to find their surprise and then come back and make a perfect plan with you. I don't think it will take too long, which will be about half an hour. Do keep quiet, please! If you get anything that you think is valuable, write it down and we'll discuss it when we meet later."

The three planes nodded and retreated three hundred meters, stopping to wait for the others who were about to go forward to reveal their surprise.

"I think, gentlemen," Photon whispered, breaking the silence, "that the spider robot will most likely allow you two to transport those poor creatures, and I can escort you."

"Oh, that's a good idea. But where are we going to fly to?" Asked Plane 2 doubtfully.

"I don't know. Let's not decide until the spider comes back." Said Plane 1, looking ahead into the deep darkness.