"It looks like sunset is still two or three hours away. Are you guys hungry? Would you like something to eat?" Asked the spider robot in a friendly voice.

Everyone felt hungry, unable to resist the stomach's call for food.

"What have you got here? All we two need is a little oil." Photon said, pointing to William and Ranran, "They two really need carbohydrates."

The spider quickly brought out a large plate of fresh pizza that had been saved and let the party feast on it. At last the mother star took leave of them, and the quiet night descended once again.

"Do you know why I choose to set out for the secret tunnel at night?" The spider asked William, hiding the small door beside the apple tree from him when they came out of it.

"I don't know. Perhaps it's because there's something in the secret tunnel that you can only see at night?"

"Almost right." Laughed the spider, "You will be surprised as we get nearer to the laboratory."

"Surprised?" Cried the others, including Black Ghost 1 and 2, shocked.

"For the time being, it's I and Uncle Sam's secret. How could you possibly know?" The spider walked ahead into the rolling hills.

Their movements were quick and agile, and they soon crossed the grassland at the foot of the hill. A few crickets were playing a symphony under the starry sky, and fireflies were holding small lanterns to light them.

When they came to a raised stone, the spider stopped and said, "Here we are, and here is the sealed hole." But when William looked around, he was disappointed to see that it was all fresh green grass. There was no such thing as a hole.

"That's because you haven't understood how to see it yet." The spider drew four lines on the stone so that they formed a pound sign. Then he pressed lightly in the middle square, and some of the grass on the slope drifted to one side or the other, revealing two doors. There was a keyhole in the middle of the doors, the shape of which matched the key they had found in the box.

"Got it? The stone was actually a writing pad." Said the spider robot triumphantly, and opened the doors with that key.

Just as they all entered, the door suddenly closed quickly behind them. Then overhead lights came on together. Ranran then saw clearly that in front was a long straight road that could not be seen to the end. The road under their feet was extremely wide, about ten lanes wide. The spider robot told her that the road was made of pressure-sensitive material and the faster an object moved, the greater the current.

"It doesn't sound like this information has any immediate use, but it will come in handy when you run away." He had again a smile, while Ranran was at a loss.

"Master, I want to test my own performance here." Natalie said, patting William's leg with her left front wheel. He agreed.

With the engine growling, Natalie spent 3.7 seconds accelerating to 100 km/h and had a top speed of 385 km/h.

"You're already good, Natalie!" Cried William when he heard this.

Thanks to the arched structure, their footsteps echoed through the empty secret tunnel. The long straight was about three kilometers long, followed by a hairpin that suddenly and sharply turned 180 degrees to the right. A 400-meter straight met it, followed by another hairpin turning to the left. According to Natalie's estimate, she could only pass at about 60 km/h in these two bends. Fortunately there was a one-kilometer straight ahead, where she could relax a bit.

"Eek, what is this?" As the party trotted along the straight after the two sharp bends, Photon caught a glimpse of a strange pipe. As he could not open it, he had to ask the spider.

But he didn't tell Photon. Instead, he said, "You'll see."

The ongoing party passed another bend, and once again saw a similar pipe on the wall of the secret tunnel. And this one went all the way into the ground!

"What on earth is in it?" William thought.

Then there were two consecutive bends. The angles were small, but it required Natalie to follow the shortest path possible. As she passed, she made a careful acquaintance, and soon decided on the method.

They walked about 1km down a straight and turned right. Before long, Ranran encountered eight hairpins in a row. Although this nightmare was followed by a delightful five-kilometer straight, yet it was the most perfect spot for the encounter with death. Because smart Uncle Sam knew that the sports car would get carried away after a long period of rapid progress, he designed this section so that he could brake too late and hit the wall. Even if he was not badly damaged, it would be almost impossible for him to catch up with Natalie again.

"Well, that sports car isn't going to keep up with Natalie." Ranran thought.

The strange pipes they had seen before would reappear every once in a while. Some burrowed into the walls of the tunnel, while others had a small box beside them painted with lightning symbols.

"Is this the distribution box?" Confused, William stepped forward to observe and accidentally caught a glimpse of a letter "B".

" 'B'?" He grew more puzzled, "What on earth is this?"

Plane 1 and 2 called him from the front, so he had to move on with the others. There was another hairpin, which was connected by a nearly non-existent straight. It was followed by another long, high-speed turn.

But they were missing one crucial piece of equipment. Perhaps because it sat on the roof of the cave, in the nature of things it should be ignored. It was a camera and radar installation, with a thin white tube sticking out beside and diving into the wall, where it eventually met the tubes they saw and ended up on a microcomputer. The computer would analyze the data from the device and eventually trigger the contents of the small boxes painted with lightning symbols.

They just needed to look up and they would see it. Unfortunately, curiosity drove them to familiarize them with this secret tunnel, so no one looked up.

This was the only device, however. This meant that if they walked right past it, they would have no chance of finding out its identity by any means other than the spider robot's narrative.

Even so, they were overwhelmed by their curiosity and only looked for the slightest sign on the road. "I saw one of those boxes again," Natalie said as she passed a thick pipe.

The road ahead was like a boa constrictor, spiraling upward. The air became still. They heard their footsteps echoing in the tunnel for a long time.

"You've got to figure out how you're going to get through here," Plane 2 said to Natalie on the climbing bend.

"Well, I will." She replied, smiling.

Once again they had a panoramic view of the delightful long straight. Natalie even wanted to fly to the bend. Photon held her down just in time.

"I want to know how close we are to the lab." Ranran asked.

"About four kilometers to go," Said the Spider, a little nervously, "and by my estimate the secret tunnel is coming to the end -- oh no, sorry, everyone. The end is in the room where the animals are trapped. But I should warn you, Natalie, that there are no lights in the secret tunnel in the underground part of the lab. So it's up to you to decide what to do with your route."

Natalie nodded nervously, her eyes fixed on the distance.

In fact, since they entered, Natalie had walked through every meter imagining the exciting scene where she would avoid the pursuit of the dreaded 5,000-horsepower sports car. She breathed a sigh of relief as her mind flashed back to the hair-raising bends just now, but she was inevitably nervous every time she reached a straight. "I'm one-fifth the power, and even if I accelerate as fast as I can, I'm not going to be much further ahead, am I?" She seemed to waver at the thought.

Then she heard a voice in the deep distance, "Come on, Natalie! You are already excellent!"

"You are already excellent! You are already excellent!" The words kept ringing in her ears.

Her eyes, full of doubt and uncertainty, brightened again.

"Hey, Natalie, what's the matter?" Photon saw her slowing down and paused to ask with concern.

"Oh, oh, I'm fine. Let's go on." She came to herself and answered without thinking, shaking the four stubby exhaust pipes behind the front wheels.

Photon shook his head. "Something must be on her mind." He said to himself.

It was here that the sports car would brush past death again -- a hairpin turning to the left, joined almost end to end by two short, continuous, high-speed bends. To get through here the fastest, it needed to brake hard as it entered the corner and could not accelerate until passing the center of the hairpin.

This, no doubt, was another area that made Natalie happy. Thanks to Uncle Sam's kinetic energy recycling electromagnetic brake system, even the fiercest beast would never rein. Plus, both William and she had mastered the most difficult bends like this so well that their error rate was extremely low.

After turning to the left, there was a straight about one kilometer long. As they spiraled upward again, the light ahead of them grew dimmer.

"It means we're getting closer to Capsule Laboratory." The spider suddenly lowered his voice and said, "All of you, listen to me. Do communicate quietly where there are no lights! Because of the structure of the terrain, if the noise is too loud, you may be detected by the lab!"

The others nodded and sped off down the illuminated final straight, into the unfathomable darkness.

William felt his heart beat faster, and he heard faint voices.

"SHH! Hush!" He hinted, lowering his voice.