All around was the endless and eternal darkness.

Suddenly, a huge shadow with a long, bright blue tail passed by. This was William's spaceship. They had been flying for five hours, and their destination was not far ahead.

"Slow down." William said, pulling his putter back gradually, "Is that the planet?"

"Yes, that's it." Photon peered through the cockpit glass and caught a glimpse of a purple planet.

After a few minutes, the ship had slowed down to the right speed and was captured by the planet's gravity. After entering the atmosphere, the party found a surprise.

"It's going to rain diamonds here soon." William pulled out a little robot, turned on the spectrograph, scanned the clouds, and said with great certainty.

"Rain diamonds?" Natalie couldn't believe her eyes, so she checked herself. But the result was no surprise -- she saw a lot of carbon crystals in the clouds.

"Wow! That's great! We made a fortune!" She cried enthusiastically.

"This is nothing." Replied Photon with some helplessness, "Our master already has such a ship. Is it not worth more than diamonds?"

"That may not be." William added, "These are crystals of carbon that we don't have on Earth or on the planet where our villa is. I'll study it when I get the chance."

He turned his head and saw two stars. "Multi-star systems are so common here," He said in an involuntary sigh.

"Yes, and there's life here, too." Ranran added.

The spaceship landed smoothly and came to a stop on a wide expanse of flat ground. After the party walked out in turn, it was discovered that what they thought was flat ground was actually a plateau. From above, some ridges were protruded from the gentle slopes, like arteries in rhythm. In the distance was an endless sea of flowers, where violets, lavender, tulips and so on were growing. They playfully twined their branches together into a huge web. On the other side of the mountain was a thick forest that stood out from the surrounding plain.

Suddenly, William smelled something strange. It spread like a vine. Then it seemed to wrap itself around William's body and his neck with great force. Gasping in pain, he rolled on the ground, clutching at something invisible with both hands, trying to break it.

"William!" Ranran shouted, hurrying forward to wrestle with the invisible object. The others gathered around.

As if the vine had feared the strength of these people, it loosened and faded away into the damp air.

"Are you all right, William?" Ranran looked at William with an anxious look in her eyes.

"I'm fine, Ranran. Thank you." He kissed her on the cheek. Ranran was at ease.

William said to himself nervously,

"I think we'd better park the ship in the forest. This is safer."

So he jumped into the ship again, made it taxi into a more open place under a tree, and finally alighted.

"Why is it so dangerous here all of a sudden?" He said to himself, puzzled.

"I think it could become the norm." Ranran also showed a somewhat worried look.

"You must be on your guard, Master. My guess is that the crisis on the final planet will be even worse." Natalie reminded William as she turned to a mushroom-strewn road.

Oddly enough, mushrooms were also machines. When they gently stepped on their feet, the mushrooms lit up on command from pressure sensors, emitting a faint purple glow. The rain of diamonds was coming, so the air was damp and the fragrance of the flowers in the deep forest grew stronger.

After stepping out of the mushroom road, they saw the green stone slabs in the soil again. As they walked, they surveyed their surroundings carefully. On both sides, the branches and leaves of the green trees crisscrossed each other, weaving into a huge green web. Some of the stout roots were above the ground, and a few stunted wild flowers were growing beside them. Occasionally, a few monkeys swung from bush to bush for amusement. William caught a glimpse of a dragonfly, but it soon flew away.

"Look! Checkpoint ahead!" Photon's sensitive eyes quickly picked up the brilliant light.

Checkpoint 10 is cleared. Energy charge: 2%.

"Our energy core is now about one-fifth full." Said William confidently, looking at the dialog box displayed on his computer screen.

At that moment, large pieces of diamonds fell from the gloomy sky. Some of them embraced the earth, some kissed passionately with the blue stone slabs at the foot of the party, and some took the leaves as a natural slide and jumped down with laughter. William caught one in his hand and stashed it in the backpack for a microscopic scan.

Underfoot, the stone slab road continued to wind. After turning several corners, they gradually ascended a hill. At the top of the hill was a tall tree-fern, which had witnessed tens of thousands of years on the planet. Unfortunately, time seemed to leave no trace on it, because the green leaves seemed to be just budding, while the trunk was still full of vitality of the bright brown. But if one cut the trunk, the dense annual rings inside would be revealed.

William stepped forward and looked up at the aged giant with admiring eyes. But when he looked down, he saw something unusual.

"Look!" He called the others in and picked up a rivet from the ground, as well as a piece of carbon fiber that appeared to be part of a plane.

"Which crashed plane could it be from?" Asked Photon curiously. "No," William disagreed, "I don't think it looks more like a crash than a deliberate discarding."

"Why?" Asked the others in chorus.

"Look at this fragment." He pointed out to the others, "If it was a crash why does it have this regular shape?"

Then the others took it and looked at it carefully, only to find that William was telling the truth. "I think your analysis makes sense." Ranran said to William, "I suggest we put it away for now. Perhaps this will be a clue, won't it?"

William put it in the backpack and continued along the stone slab path. They went down the hill and found another piece of carbon fiber in the plain. The two pieces fitted together seamlessly.

So without thinking, William said,

"I think it's time to rule out the possibility of a crash because this fragment also has a very regular shape. If you must say that a crash could have produced a lot of fragment like this, I would rather it's false."

The party continued along the stone slab path, and gradually they came to the edge of the forest. The trees were arranged in neat rows, revealing a wide road covered with emerald leaves. Behind the last row of trees grew a clump of colorful wildflowers, and in the distance was an open plain again. The rain of diamonds gradually stopped, and the crimson afterglow of the falling two mother stars filled the sky.

"Wow! Look, it's a rainbow!" Ranran excitedly pointed to the horizon, her face brimming with a bright smile.

"How beautiful. I hope we get a beautiful rainbow like this when we come home," William said softly, staring at the uniform ribbon.

"Certainly, there is no difficulty that we cannot conquer, as long as we believe in ourselves." Ranran replied, with a faint smile on her lips.

After advancing one kilometer or two more across the plain, they came to a sign. It read,

To the hangar, please proceed to the tunnel.

"Hangar? What hangar?" Confused, William had to walk along the stone slab path. It spread forward and eventually disappeared into a tunnel. They entered the tunnel, climbed a few steps, and saw an iron gate.

"Let's go and see." William opened the gate. A tunnel spiraled up ahead before the surrounding area opened up. They watched as they advanced, and in the end it was not in vain. Walking to a stone, Photon found some graffiti on the wall.

He did his best to read the patterns. After several intricate patterns of random lines, an airplane appeared on the wall. Her streamlined shape suggested her endless pursuit of speed, while her steadfast eyes symbolized that victory was her only choice. As Photon looked closer, he saw a retractable float hanging under the fuselage with a handle beside it.

"Can it be a mechanism?" Out of curiosity, he shook the handle. The stone that had been painted the float was lowered slowly to reveal a note. He read,

I used to dream of crossing the finish line like a flash of lightning. Yet now I can only stop in the hangar, ruthlessly puncturing the beautiful dream.

Confused, he asked,

"What is all this?"

In the end, he couldn't answer the question, so he followed the others and moved on.

Natalie picked up another fragment, which also fitted together with the other fragments.

"What does this mean?" She said to herself.

"I now think it's possible that these fragments were designed by someone who wanted us to use them to find something." William's casual guess unexpectedly got the unanimous agreement of the others.

"It makes sense." Ranran said, "Maybe we'll soon find the person who designed these pieces."

The few remaining fragments were found one by one, and at last they formed the shape of a five-pointed star.

"Are we supposed to put it somewhere..." William looked over and over at the pieces he had put together, faltering.

As they spoke, they came to another door. Ranran noticed the words on the door:

The hangar has been reached.

Then a slot in the shape of a five-pointed star popped up. By comparison, William was pleasantly surprised to find that the two matched perfectly. Without thinking, he put the pieces in. After a few circles of slow rotation, the slot made a sound like an unlocking sound. Then the door opened.