The party turned on the computer and checked out the next destination. "This is it." Said William, still not completely calm, "We'd better go through the checkpoint first."

"It's all right, William." Ranran comforted him.

He wiped the tears from his eyes, glanced back, and continued to follow the map until Sophia's cafe was completely out of sight.

At full speed, the party passed Checkpoint 4 at the 7km road sign. "The energy core gained another 1.5% of its power. That's great!" Natalie said excitedly.

"Almost there." Said Photon, glancing at the map.

Then the outline of a magnificent building began to unfold in front of them. The air was still wet due to the snow that fell last night. In the distance, the water mist in the air reflected the colors that blended the blue light of the mother star with the golden glow of the outer walls. The streets were still full of voices, drowning out the melody of birds in the distant hills. They also saw the bees circling round them several times, scattering a sweet violet fragrance to them, and then flipping away. And as they walked on, they heard a clear sound in the golden building,

"Ding-dong -- ding, ding, ding, dang -- tick, tick..."

"It sounds like a music box," Ranran said.

Then the sound went on,

"Woo-woo, woo-woo..."

"I think it's a saxophone voice. Or a trombone." Photon said.

"Listen to the piano playing!" Natalie exclaimed excitedly, tugging at William's skirt.

"Yes, and the harp and fiddle." He laughed.

"So is that a... Oh! Good heavens, what is this!"

Before Ranran had finished saying, a note flew straight at her and landed in her face. It was a brief description of the building.

Help letter

Dear Friends,

Did you hear that beautiful music just now? Yes, this is the famous Warner-Wilson Concert Hall. It is the only concert hall on this road, so many famous performances are held here. With its magnificent decor, clever structure and complete and professional equipment, the concert hall is able to leave you feeling alive ten minutes after a performance has ended. And its purpose is to let you indulge in the sound of nature, and let the soul fully accept this holy bath.

But recently an unpleasant thing happened to the concert hall --- the instruments suddenly all disappeared! There is still no trace of them. The only clue is that one of the spectators entered the room and accidentally found an abnormality in the floor where he thought the instruments were hidden, but he didn't look into it. After that, no spectators came to the show.

Please kindly help me find the musical instruments in the concert hall! Otherwise it won't be long before it goes out of business! If any good-hearted person can successfully find the whereabouts of the instruments, on behalf of all the staff of the concert hall, I would like to extend the highest respect to you! In order to thank you for your help, we will also create a set of all the classical instruments in the universe specially for you!

Thanks again for your help!

Grateful director Warner-Wilson

2135.7.20

"Oh?" After Ranran saw it, she couldn't help but be shocked.

"Today is the 26th, so the letter must have been posted about a week ago." Muttered William.

With these words, they entered the concert hall. Looking up, they saw millions of golden lights hanging from the ceiling, which was about ten meters high. The atrium was surrounded by glittering glass. This height was deliberately considered so that they would reflect the lights' golden light to the maximum extent possible. The walls were lined with high and low scattered speakers, whose use made it possible to 100% restore both the sometimes deafening unison and the sometimes low and tactfully solo during the performance, and show it to the spectators incisively and unreservedly. Looking around, the comfortable red seats occupied almost all the space on the upper and lower floor. There were more than fifty rows in total, each holding an average of seventy spectators, and the largest row was the last row on the second floor, which could hold one hundred spectators! Underfoot, the solid, textured rosewood floor tiles served two special functions -- first, because they were immersed in the rosewood juice before they were laid, they could give off for a long time the natural, unvarnished aroma of the forest. Second, they had built-in magnets so that when someone stepped on them, the floor deformed -- although this was not obvious -- and the magnets would move due to this, generating electricity from the coils below. According to the incomplete estimation from a staff member, the concert hall could save millions of dollars(conversed) a year after this kind of electricity-generating floor was equipped.

As they were looking at the luxurious environment, the party exclaimed. They walked across the atrium, up and down the stage, and then walked straight up to a door. This was strange, for they had no one to show them, but the door which they came toward was the office of Warner-Wilson, director of the concert hall.

"What is it that guides us?" Thought William, puzzled. Photon knocked on the door.

"Come in please!" A somewhat hopeful voice came from within.

They slowly opened the door and saw a handsome man sitting anxiously at his desk. William looked at him and saw that he was wearing a dark black suit over a white shirt, which clearly set off his blue, gold-edged tie. Below the black pants were the shiny shoes, reflecting the light of the mother star outside the window. His shiny black hair fell neatly over his broad head, and his dark eyes were mirrored by thick eyebrows, giving the man a distinctive look. He was supporting his drooping head in one hand, and his eyes were closed. He was at his wit's end. Careful William also noticed a W-W logo pinned to his suit.

"It must be him," He thought, and he asked politely,

"Are you Mr Warner-Wilson, director here?"

"Yes, it is me. May I ask who you are?" Replied the man, looking up at them too.

"I'm William, this is Ranran, the plane's name is Photon, and the racing car's name is Natalie." William introduced the others briefly, then changed the subject and said, "We've just seen your request, and we didn't see any instrument when we came in. But the strange thing is that when we were outside we could hear the instruments playing, and then suddenly they weren't there."

"That's normal, William. Perhaps you were only imagining it." Wilson said.

"Impossible, Sir. We heard it very clearly."

"Really?" Wilson was a little incredulous and wanted to make sure. William nodded firmly.

"Then I don't know. At least I didn't hear it. Not before you came." He replied.

"Listen, there it is again!" Sensitive-eared Photon touched William with the propeller and signaled him.

But the voice soon died away, as if it had never been there.

"I heard it just now, but it's gone now." Wilson said emphatically this time, "I'm sure I heard it."

"Shall we go out and have a look? By the way, we'll go under that floor, too, and see if you can find your instruments." Ranran volunteered.

"Really? This is the first time anyone has offered to help me. If it's true, great!" Wilson's eyes sparkled with hope, and his hesitation was now fleeting. There was finally a smile again on his face -- the last time he had smiled was half a month ago.

They opened the door and looked out, but saw nothing in particular. The sound of the instruments began again. "Over there! Hurry up!" Wise William caught a glimpse of a shadow passing by and running toward the particular floor tile. Wilson thanked them again, and they followed the shadow closely.

But it was very naughty. Just as it was about to reach the floor tile, it flew up again instantly and reached the second floor.

"Keep up with it!" William ran to the stairs. His legs went fast, and he ran up thirty steps in ten seconds.

"I wish you could fly and teach it a lesson," Natalie said to Photon.

"But it's not long enough! I need about 400 meters of smooth road to take off. And in such a small space, I'm bound to stall. Even though my wing load level is moderate, at 180 kilograms per square meter, flying at less than 150 km/h is simply killing me."

Upstairs, William followed the shadow in hot pursuit. Seeing this, the shadow flew downstairs again.

"Aargh! William, are you going to die!" Ranran let out a scream. William jumped straight down from the second floor. Fortunately, the planet's gravitational acceleration was not particularly strong. He landed smoothly and ran after the shadow again.

The shadow jumped up and down in the concert hall. Everybody was gasping for breath, but they still could not catch up. The shadow gave a groan of snicker, and then dived under the floor.

"Whew, he's in at last. I'm exhausted! Go, keep chasing!" Gasped William, sprinting to the floor tile again.

When he stepped on it, the floor tile jumped aside. Several floor tiles next to it also jumped aside, revealing a hole big enough.

"We must find the instruments!" Said William loudly, jumping down.

"We never fail! We never fail!" The others followed, disappearing into the darkness.