After saying goodbye to Maria and Uncle Sam, the party continued down the road. Photon and Natalie did not know whether it was because of the transplantation or not, yet they both felt unusually as light as swallows.

Checkpoint 7 is cleared. Energy charge: 3%.

This was what they got after covering two kilometers.

"It's strange that I'm not tired at all." Said Photon, and he began to sing a little song easily.

"Really! I feel light, too." Ranran said with a smile, "I wonder what special things Uncle Sam has there."

"Maybe it's his skill set and his sincere love for car modification." William thought for a moment, then replied.

The mother star gradually climbed above them. The snow melted faster and faster, and the temperature cooled further, but it was not cold enough to chill because the mother star was still baking it. At 21km, the snow had largely disappeared, and the road showed its bright black face of tar.

After passing 22km road sign, the road gradually grew deeper into the mountain, and also slowly narrowed. Finally, at 23km, it used a huge rock as its end. Passing the rock, the party suddenly saw the silhouettes of mountains rising and falling a short distance away. Although they were only a few hundred meters high, the landscape they formed was more magnificent than that those peaks thousands of meters high on Earth would form. Closer still, they saw low grass on either side. Ahead, thick green trees wove beautiful coats, letting these big bald guys have a bit of life. William could see the multicolored wild flowers at his feet, smell the violet and hazel trees on the hill, and hear the song of the thrush in the woods. A fresh spring rushed down from a distant hillside, and at last flowed into the sea in the east. Ranran sprawled on a strangely-shaped stone. She could not help but hear small, magnified sounds from the inside of the mountain: the tinkling of water against stalactites and stalagmites, the crawling and chirping of small creatures, and a noise she could not tell.

"We'd better find the planes first." William could see the thick forest behind the hill. It turned out to be the right direction, for it was just front-left to the end of the road.

They sprinted down the hill and stepped into the level grassland in front of the forest. Looking at the tender grass and listening to the songs of the sparrows, Ranran couldn't help laughing, showing her white teeth. It was not much grass, and soon they came to the edge of the forest. "Let's go in," Said William, moving forward without hesitation. The others followed and entered.

Looking up, the light of the mother star felt warm, gently touching the heads of the party through the gaps in the wide web of lush leaves. As for the thick trunks, it took half a dozen men hand in hand to circle them. The huge crowns that made up the net were like the trees' long, soft hair. Orioles and butterflies could be found occasionally in the branches, while smaller crickets, spiders and snakes could be found at the roots. Underground were moles and earthworms, which picked up fallen leaves and carried them home to be processed for other purposes.

"What's that?" Said William, pointing to an M word a few hundred meters away, so they all went over and stamped their feet five times.

A magical thing happened: a few rows of trees on the right side suddenly receded automatically, revealing a well-hidden path. They turned and saw a kind of foot print in the path.

"This must be Uncle Sam's, because I noticed the outline of his leather shoes, and it fits perfectly with this one. So he must have been here." Careful Photon analyzed.

The path winded down and down. At last they came to an open place and found a wide opening. Natalie noticed a propeller sign painted above the opening.

"This should be what Uncle Sam was talking about." She said, "But it is so dark inside that I am afraid."

"It doesn't matter." William bravely rushed in, but as soon as they were inside there was something threatening.

William had his laser gun ready and held it tight in his hand. "Let's keep our voices down. The echoes are good here." He whispered. It was so empty that even their soft footsteps reflected off the arched walls.

It was getting darker inside, so dark that they had to use a light source. By the dim light, William could see a kind of graffiti on the wall every a few steps apart. There was nothing special at first, but when they reached the fork in the road, the last graffito on the wall suggested they turn right.

They climbed down a spiral staircase and saw two huge, dark figures standing motionless opposite each other in the wider and darker tunnel in front of them. They approached slowly, somewhat doubtful. As they got closer, William could tell from the outline that it was the planes Uncle Sam had told them about.

Suddenly all the lights around them came on, alarming them.

"Nothing," One plane said. His voice was not loud, but he frightened them.

Still nervously, William raised his laser gun, staring around, his finger edging closer to the trigger.

"It's me," The plane said again. William then turned around and put the gun down, but he still couldn't believe it was the plane.

"Is it really you?"

"Yes, it's me, Black Ghost." The plane continued, "You must have just come from Uncle Sam's."

"You guessed it, but how do you know?"

"Because Uncle Sam was here just now. He should be back in the garage by now."

"What? He's been here? Then why didn't we find him?" Ranran asked in surprise.

"He won't let you find out the secret tunnel. He came from the corner. After this comes the long straight road to the garage, which he has built himself. Hey, man, wake up! Someone's coming!" Said the plane to the opposite one.

"Who is it, Yawn... Oh, sorry, I was just sleeping." The plane opposite said. The party turned around and saw that they were very similar.

"Are you twins?" Asked Photon, "I don't think you look like fighter-bombers. At most, you are reconnaissance planes and bombers."

"Oh, you really talk big." Said the plane opposite, "If you don't believe it, why don't we go up in a moment and compete for horizontal circling and nose directivity? By the way, I haven't introduced myself yet. We're both called Black Ghost. He's Plane 1, and I'm Plane 2. You can tell by looking at the numbers on the vertical tail."

William introduced the others to Plane 1 and 2. "Nice to meet you." William stepped forward to shake hands with them in a friendly way.

William cleared his throat and said, "We heard from Uncle Sam that he too had heard that the gene-edited cat was trapped in Capsule Laboratory so he had sent you and a spider robot to spy. We are here to ask for more details and find the spider so that we can go together to Capsule Laboratory to rescue the animals inside."

"Oh, I see! So you mean you walked all the way from Thomson's tree house, too?" The eyes of Plane 1 gleamed with excitement.

"Yes, but we don't belong on this planet, much less in this universe."

"What do you mean?"

"We're actually from another universe." Natalie answered, taking William's words.

"What?? Oh my God! There are people from another universe!" The two planes were astonished, "Have you mastered the technology of space travel?"

"No. It's just that my father was involved in the study and gave it to me on a trial basis. Whether it can go public on our planet remains to be studied." William replied.

"Oh, all right. We've met aliens before, but this is really the first time we've seen aliens like you." Plane 2 shook hands with William again and continued, "You are here to rescue the gene-edited animals trapped in Capsule Laboratory, am I right?"

"Exactly." Replied Photon, "In other words, it couldn't be more correct."

"Good. May we ask you a question first: how much do you think it will actually cost to get out of there, and what is the chance of success?"

To the question of Plane 1, the party gave their own answers.

William replied, "I think you need to at least study how the security system works and make a plan for that so that you can get around them better. Personally, I think it's not hard to do this."

"You also need to know the terrain around the lab, so you can choose the best escape route and not be recaptured." Said Ranran, "For that, all you need is a map, and it shouldn't be too hard either."

Photon and Natalie had similar opinions.

The two planes listened attentively to their analysis, then smiled and said, "You underestimated."

The party's hearts sank to the bottom at once. "To put it this way," Said Plane 1, "we two and the spider had Uncle Sam build an extra secret tunnel underground and seal it with a code that no one else could crack. As we approached the lab, we chose a night. I flew high in the sky with Plane 2 to spy, while the spider sneaked inside. It took us about two hours to come to the conclusion that if we had not built the tunnel and did not use air transport, it would be impossible for the animals to escape."

Every word echoed through the empty hole. Plane 1 continued, "Our investigation shows that their security system on the ground is very good. The laboratory is surrounded by a wall tens of meters high, with a high voltage of 500 kV. The surrounding mountains are full of cameras, and it's almost impossible for them to damage long enough for all the animals to escape. And to top it all off, the lab has a nearly invincible sports car equipped with a 5,000-horsepower engine that allows it to reach a top speed of 560 km/h!"

Natalie broke into a cold sweat. "Yet, ha ha," Said Plane 1 again with a sneer, "we found two weak points in that lab. The first is the midair. Naively believing that no planes will come, they are not even equipped with anti-air weapons. The second is the secret tunnel, which their security system never detected."

"Ah, that's good." Ranran breathed a sigh of relief.

"So if you're going to be successful in saving all the animals and maintaining the integrity of those unique genes, we're going to have to act together. And it's got to be a perfect plan -- yes, I'm right, a plan without bugs!"

The others shouted "Come on!" but William said anxiously, "Perfect plan? Huh, what's Natalie going to do if that sports car finds her?"

"Rest assured, your Natalie will be fine." Both planes replied in unison.

So William was relieved for the time being.