Two mother stars used bright light to wake the party sleeping in Room 413 of Lavender River Valley Inn. Looking out of the window at the red sky and listening to the birds singing merrily, they sat up, rubbing their sleepy eyes and yawning.

"Let's go." Sierra said, "I'll take you to my plane."

So they followed her downstairs, out the front door, and turned right onto a path of glowing mushrooms. After several bends, the road came to the river that William had seen when he first reached Lavender River Valley. The river scattered the gravel along the bank, playing the piano of nature. The air by the river was a little damp, but it did not affect the spread of lavender's fragrance.

"Oh, it would be perfect if we could find such a nice place on Earth." Ranran whispered in William's ear. He smiled and replied, "Don't you think the undersea villa would be perfect? If you want other environments, we can simulate them with VR Ultimate, an app on my computer."

"Oh, I didn't think of that!" Smiled Ranran, "It's just that the effect may not be as real as being there."

"Yes, however realistic it is, it can only be a simulation."

The path of glowing mushrooms ended, and some steps appeared in front of them. The party went up without hesitation. When Photon reached the last step, they faced an open level. On all sides were not very steep slopes covered with lavender. And in the middle was a huge circular area with a gap on the edge.

Natalie couldn't understand why there was a gap. "You'll find out if you come with me." Sierra said, letting the others to move to the center of the circle. Then she stepped in and drew downward on the ground three times, and the circle lowered itself until it touched the bottom.

Lights came on and Sierra signaled them to come down. Sure enough, the plane was there. At first glance, however, he looked a lot like the cocky airplane Jackson that William had encountered after leaving Woodford Refitting Factory. "Am I dreaming?" William could not believe his eyes.

After much reassurance, William was convinced that it was not Jackson. The plane told them that his name was Peter and that he knew Jackson. Their painting was very similar because they were all made in the same factory. "The factories that assemble the racing planes have many branches, and each branch has one or more paint solutions." Peter said.

"Peter is going to take you to a lighthouse," Sierra said, "because there is something very special there."

"Oh? What special thing?" Ranran asked curiously.

"You'll see when you get there." Replied Sierra mysteriously. She led the others up to the ground and followed another path of glowing mushrooms to the foot of the lighthouse. William looked up at the white giant: it was particularly huge, plunging into the ground like a nail. The white paint on the exterior wall had not faded a bit, and was still as bright as jade. It could even show color in the light of two mother stars. About 300 meters above the head was the top of the lighthouse, inside which was placed a very powerful high-brightness laser light. It got its power from turbines hidden in the river, which were driven by currents and temperature differences.

When it comes to why a lighthouse was installed there, Peter explained that a further 1.5km to the south would lead to a wide expanse of ocean, except that some slope in front of the party blocked the water from their view. It was easier to install lighthouses here.

"Let's go in." Sierra said.

They opened the door at the bottom of the lighthouse and stepped in. But the moment William's foot went in, the atmosphere suddenly grew heavy. The air seemed to stop flowing, and then, as if controlled by an invisible hand, it all piled up toward William. Soon he felt severe pressure on his neck. He was breathing hard, his veins bulging, and his forehead was thick with sweat.

Ranran was very anxious to watch, and so were the others.

An angry voice said, "Why are you walking so fast! Tell me!!!"

"You won't know any detail!" William shouted at the top of his lungs as he tried to breathe, "Your plot... Won't work! We... Will go back!"

"Stop dreaming!!" The voice grew angrier.

William fell to the ground, looking miserable. "You...... Go to hell!" He cried. At last the voice died away, and the hand stopped clinging to his throat. The air became normal again.

"Are you all right?" Concerned, Sierra and Peter asked, "Who's that guy? Why would he do this to you?"

"I don't know his identity, but it looks like he knows me." William replied, "Actually, I'm an alien, and I don't live on this planet. I want to go back to my home, but he doesn't want me to go. His plan is to make me die, instead of going home smoothly."

"Oh, poor William." There was a sadness in Sierra's eyes, "We were all scared. But it's good that you're okay. Let's go up."

The party began to climb the stairs to the top of the lighthouse. Suddenly Peter grabbed William. "It's a sign I've never seen before. Be careful." He said, pointing to a triangular area. William looked in the direction he indicated, and saw that the area on the wall was black and covered with black smoke.

He felt bad. "It's probably from You-Know-Who." He thought, "Let's get away from this and get to higher places."

But things were not getting better. He saw the triangular area again. "Run." William said to the others, "Hurry upstairs and get to the top." But it didn't work. After climbing dozens of steps, he became aware of a white figure walking around.

"Danger!" He thought. Suddenly the scene in front of them darkened. The party was puzzled: obviously, they were still standing on the stairs, but why the scene became a little dark?

A small robot crawled out of the backpack and into William's palm. He told William, "While you were sleeping last night, I put an invisibility coating on each of you. When necessary, I will perform the operation, and the coating will change to the color of the environment, allowing the light you reflect to pass through your body. Then you will become invisible."

"I see." Rebecca was enlightened.

"Now you can go upstairs safely!" The robot went back into the backpack.

The party was still a little uneasy. They slowed down and stopped just before they nearly hit the white shadow. From below, William could just get a good look at it. It was a spherical camera, looking around for something.

From under the lighthouse came a note. It read,

What's the most effective way to make an object invisible?

William laughed secretly, "It's a piece of cake! The little robot just told us -- well, even if he didn't tell me, I know that objects can be seen because they emit or reflect light, and the light is picked up by detectors. So if you want to make a luminous object invisible, you can put it in a black container that absorbs all the light it emits. It's even easier to make the object invisible that reflects light. Just let light pass through."

Surprisingly, the camera descended from above, past William and his party, to the bottom of the lighthouse, where it disappeared.

"Oh?" Ranran found this incredible. She blinked repeatedly to make sure that what she had just seen was true before she dared to continue going upstairs.

After that, though the air was still a little heavy, it was not quite the same. William finally relieved a bit.

"I don't believe it was meant to be so terrible." He said to Peter, "Because of that man, this happened."

"You're right." The plane replied, "The lighthouse is in good condition. It was meant to serve the ships of the sea in silence. I don't understand why the You-Know-Who you talked about is here threatening you. What was his intention in choosing such a place? Why doesn't he want you to come home?"

"I can't answer either of these questions." William said with a sigh. The plane was silent.

"But anyway," William said to Peter as he climbed the stairs, "I've got to go back. Since that person does not want to see this result, I will fight him to the end! I'll show him who's the stronger man!"

It was not clear what magical power his words had, but the air was no longer heavy. It was even like outside the lighthouse. William also found himself less afraid of being threatened by You-Know-Who. He thought it had something to do with the encouragement he gave himself.

"Most times it was because I lacked confidence and was too scared." He thought, "I don't know why I sometimes didn't want to believe I was ever going home. I remember seeing my own thoughts when James the firefly took us to the prophecy door. I have not reached the last planet, where I may still be afraid. But I don't think I'll be always afraid."

At last they reached the top of the lighthouse. Time flew by imperceptibly, and in the twinkling of an eye the day was coming to an end. Stars grew up to take the place of the two mother stars. Ranran noticed that one of the brighter stars was casting its light into a small cabinet under the laser light.

Sierra turned the lock on the cabinet and opened it. Inside was a small key, shining in the bright starlight.

"What can it open?" Ranran and Natalie asked together.

"A cabinet, too, yet not in this lighthouse." Peter explained, "Let's turn on the light before we go down."

Then suddenly there was a whirling beam of light on the dark sea. They watched the laser light rotate. After a few minutes, they turned back and walked downstairs until they were out again on the breezy lavender field.