The two mother stars were about to leave for the other side of the planet, and violets reluctantly saw them off. William could hear them complaining, "We haven't enjoyed your light yet. Don't leave so soon."

"Let's hurry up to the castle." Ranran said.

"What castle?" Natalie asked, puzzled. So Ranran opened the map and showed it to the others.

About five kilometers away, they saw the castle they were going to. There were several checkpoints on the way and there was no other route, so they had to follow the marked route.

The party immediately set out quickly. After passing Checkpoint 19 and 20, the energy core was charged with 5% more power. At last the outline of the castle became clear. When they got under the gate, William could finally look at the tall building. It had a network of domes, high and stout towers reaching into the sky like pillars. Flags with butterflies on them floated over the town walls. Under the shining stars, the colorful paint glowed, making the castle a rainbow falling from the sky.

Photon's keen eyes detected something flying. So he took out small fireworks in the backpack and lit them. Gorgeous fireworks exploded in the air, attracting the attention of those objects. They flew down and stopped in front of them. Rebecca discovered that they were colorful butterflies.

The largest butterfly landed lightly in William's palm, flapping its colorful wings and shaking two long antennas on its head. After a moment it looked up and smiled at William. The smile was so sweet that it made him feel the friendliness. So he smiled, too.

"Hello." Said the butterfly, "Are you William?"

"Yes, it is me. But who told you my name?"

In fact, William already knew the answer. Before the butterfly could answer, a little robot poked its head out. "It is getting late." Said the butterfly, "You had better go to the castle and have a rest."

"Ah..." Ranran hesitated. She did not know what was in the castle, and thought they might be in danger at any moment. "It's OK, friend." Said another butterfly, "I understand your concern. We're friendly. No one's going to hurt you, I promise. You are so tired that you had better hurry into the castle before it affects your health."

Seeing the butterflies' complete lack of hostility, the party was confident enough to follow them into the castle. Tall towers stood and thousands of butterflies were dancing happily in the air. At their feet was the path of glowing mushrooms, by their side were luxuriant flower lights, while overhead was the gorgeous starry sky. It seemed to Rebecca that they were dreaming, but their senses were clear. "I wish I could stay here forever." She thought.

A butterfly led them into a tower. They climbed a staircase made of vine and wood and entered a room. The scent of lavender was in the air, and the purple stickers on the walls looked elegant. Perhaps because there was magic here, the party were unable to fight off the overwhelming drowsiness, lying on the light bed. Butterfly found lavender quilts and placed them gently over William and Ranran.

"We should have taken some sleep capsules." Muttered Photon.

"Come on, that's no real substitute for sleep. You'd better sleep." Natalie said.

As soon as they were asleep, butterfly flew quietly into another room, took out a bottle of liquid and sprinkled it on each person's forehead. A strange thing happened -- one after another, beautiful butterflies came out of their clothes, fluttered out of the window and flew into the street. "They will love it." Said the butterfly, "It will rest them and give them a good view of the castle."

These butterflies were bionic robots that would go out to record video while William and his party slept and store it in tiny internal hard disks. When it was needed to play, the hard disks could be taken out at any time. The party had just fallen asleep when some butterflies flew into their clothes and hid the robot butterflies inside their clothes.

That butterfly flew back into the room it had just entered and pulled out some eyeglasses as well as a curved screen. Then it stopped on a wall, gently placed those glasses in front of everyone's eyes, and hung up the screen. It flew up and pressed a button. What the butterfly robots saw appeared on the screen and in the glasses. The flower lights were brighter now, and the blooming flowers also sent out a refreshing fragrance. The path of glowing mushrooms began to change color. There were countless beautiful butterfly robots in the street, some of whom spread their wings to fly, some stopped to rest, and some, in small groups, began to dance.

The party seemed to wake up. Their brains received the images from the butterfly robots, and they began to talk. However, they were actually still resting, and it was just that they seemed to be awake.

"Look! Butterflies dancing!" Ranran gently nudged William beside her, "How nice!"

"Where?" "There!"

Ranran held out her hand to point, even though she was actually pointing at somewhere in the air. William saw it, and exclaimed. This was thanks to the analog stereo technology used in these glasses, which could even simulate the five senses of seeing, hearing, smelling, tasting and touching, making the experiencer really in the scene. Even it was now in the 22nd century, this was still a fantasy for earthmen.

Photon, Natalie and Rebecca saw a huge garden at the end of the road. As the butterfly robots flew forward, they felt a stronger and stronger aroma. When the robots entered the garden, they were greeted by a vast expanse of violets and lavender. Beside, there were canna, tulips, sunflowers and so on colorful plants. "This garden is really nice!" Cried Rebecca.

"Yes, I want to kiss them. They're just so beautiful." Natalie nodded.

"Hopefully there will be a lot of places like this on Earth." Photon said.

The next thing they saw was that the camera turned left. The robots were making their way to the big lake. The night sky hung over the land, the water was clear and the wind was calm. There were some butterfly robots gathered here. They flew fast and lit up the lights on their bodies, forming a beautiful picture. Then they rearranged themselves, showing all sorts of patterns. Viewed from above, it was simply the twinkling stars flying.

"Wow, that's great!" Rebecca said excitedly, "This is unbelievable! I can't believe there are robots' performance!"

Then the bionic robots began to fly toward the towers. The stars still shone and the colorful paint gave off an iridescent glow. The flags at the top of the towers fluttered in the wind, and the butterfly robots danced with it. One moment they would rush out of the clouds for a while, the next they went into the embrace of the earth. Straight lines, curves. They created beautiful patterns. These little guys were artists.

The robots entered one of the largest towers, where warm lights lit up. William saw the robots fly down a long corridor. As if knowing that the robots were coming, the corridor suddenly woke up. The walls slid slowly. From inside the walls flew out a few elves who used the magic wands in the hands to pat the paintings on the walls gently. Then came the armored cavalries, mounted on their horses, wielding spears. The butterfly robots, elves and cavalries started to perform a joyous dance: the butterfly robots landed in the palms of elves and bounced on the armors of cavalries; the elves and cavalries acted as a bridge over which the robots flew. The show ended and they said goodbye to each other. The elves and cavalries returned to inside the walls, while the butterfly robots continued their flight inside the tower.

They came to a huge harp. A little robot touched a string with its wings, and the harp began to sing by itself. Beautiful melody echoed in the air, like a spring flowing into the hearts of William's party. It could eliminate all sorrow and despair, and bring all joy and happiness.

The highlight came: a magic carpet floated down from the sky, gently landed on the ground and signaled the butterfly robots to board it. Moments later, the magic carpet took off and circled the entire castle. On the walls, William saw twinkling stars, dancing gift boxes, whirling magic sticks, and flying potions. Directly galloping was a golden airplane who pierced the sky like a blade and sped across like a lightning. Then she got a gold medal on her hood, the cheers and applause going through the air.

William's heart warmed, and he thought, "This must be the butterflies' blessing to Rebecca."

Finally, all the butterfly robots returned to the tower William had entered, and quickly re-positioned themselves. Half a minute later, they turned on all their lights. A huge heart-shaped pattern appeared in front of the party. The robots drew a circular path in the air; a few robots flew out of the line, formed a small heart-shaped pattern, and danced happily.

Rebecca exclaimed excitedly, "Unbelievable! Perfect!" The others smiled knowingly, too.

"Well, the sightseeing is over." Said the butterfly in William's room. It pressed the button again, and all the butterfly robots went back to their places. The robots that sent back the picture flew straight away.

"Go to sleep, friends. The castle will give you the most fantastic experience." Said the butterfly, and quietly took back the glasses and the screen, flying away.

Rebecca said to Photon and Natalie, "Wow, that was a great sightseeing! Think of all the beautiful things we have seen!"

"Indeed. Maybe we will never see a better place." They two answered.

Only the sleeping party was left in the room. Bright stars shone on the purple stickers on the walls, and the scent of lavender was still strong. It was so quiet that only William's and Ranran's breathing could be heard. Outside the window, the air was fresh and cool, and the flowers had fallen asleep. The breeze, willing to be their cradle, went merrily along, humming a lullaby. The path of glowing mushrooms glowed with a faint purple glow, while flower lights stood quietly on both sides of the street under the night sky. The towers of the castle were still high, with flags flying in the wind.

Beyond the castle, all was asleep. Hans the engineer's windmills stopped spinning, and the mushroom pianist lay on his bed in the cabin. Even the vegetables and fruits in the secret growing base were asleep. The grass on the plain snored with bent heads, the violets slept with closed eyes, and the woods were far from the noise of the day. No more noisy rivers, no more singing birds. Nothing made a sound, for it was afraid to break the silence of the night.