"What is this?" Bella noticed some white powder on the floor.

"This is ......" Mrs. Frida tilted her head, looking confused, "I don't know......

"Was it clean when you first cleaned it before?" Elena asked.

"It should be...... Right?"

Afterwards, Mrs. Frida called the maid who was in charge of the cleaning.

"Fanny, what is this?" Mrs. Frida asked, pointing to the powder on the ground.

"This ......" The maid named Fanny was also surprised to see the white powder on the floor, "I promise the Virgin Mary that there was absolutely no such thing when I cleaned it before!"

"When was the last time you cleaned?" Bella asked.

"Yes...... It was last Wednesday."

"Huh? It's been over a week!" Mrs. Frida looked a little surprised, "Didn't you say you should clean at least once a week?"

"Yes! I'll clean it up."

"Wait," Bella said, "and we'll see if we can find any useful clues."

"You go down first." Mrs. Frida commanded.

Fanny answered and left the room.

Bella continued to search.

The clothes in the wardrobe are relatively neat, as if they have just been washed, and they have not been stored for a long time. But the beds are flat.

Elena was concerned about the powder on the floor, so she wiped a little with a napkin and sniffed it close to her nose.

"It's—" Elena couldn't help but frown.

There is a pungent smell.

"What did you find?" Bella asked.

"It feels like saltpeter." Elena replied.

Why did saltpeter powder end up in Mr. Frida's room?

"Excuse me, what does Mr. Frida do?" Elena asked.

"Uh...... Let me think about it." Mrs. Frida thought for a moment, then replied, "I don't know."

"Huh?" Elena was stunned, "That's your husband! How can you not even know what he does?"

"This ...... I only know what he does at the University of Paris, but I don't know." Frida said with an innocent look on his face.

"Okay." Elena said she had nothing to say.

Bella continued to check the other corners and found nothing suspicious.

However, judging from the smell in the air, it is true that this room has not been inhabited for a while.

"Still can't help it?" Mrs. Frida asked worriedly, "Could he really be in any danger?"

"No way, there are too few clues." Bella replied.

With only such a few fragments, there is no way to piece together a complete pattern.

"How about that?" Mrs. Frida said distressedly, "In a few days, it's time for the Deros family!"

You're worried about your husband!

"What now?" Elena asked Bella.

"Hmm......" Bella said after a moment's thought, "let's go to the University of Paris."

Immediately after, the three of them set off.

The University of Paris was converted from the Sorbonne. Although the school was founded to teach theology, it has grown over the centuries to become a comprehensive university. It not only encompasses mathematics, physics, history, astronomy, geography and other fields, but also revolutionizes the structure of the school. Therefore, it was renamed the University of Paris and reorganized into a comprehensive institution of higher learning.

After much inquiry, Bella and the others finally found the scientific research laboratory where Mr. Frida was.

However, none of the other colleagues here knew where Mr. Frida had gone, and even some of the new interns had never met Mr. Frida.

"How so?" Elena wondered, "Could it be that the world has evaporated?"

No, according to the current situation, it can indeed be regarded as the evaporation of the world.

However, the people in the lab didn't seem to care very much, as if they were used to the absence of such colleagues.

On the other hand, there are at least a dozen desks in the office, which are empty.

After inquiry, I found the seat that Mr. Frida used in his office on weekdays.

The table was neatly tied, but no dust had accumulated on the surface.

In the front right of the table, there is a calendar, and a circle has been drawn with a red pen in the place of tomorrow's date.

On the table, you can't find items that you use every day, such as quills and teacups.

"Interesting......" Bella muttered.

"What?" Elena nervously asked, "What's wrong?" What's wrong? Do you have a clue?"

Bella laughed but didn't say a word.

After the three of them left the research room, they first went back to Madame Roland's salon.

"What are we going to do next?" Elena asked.

Just seeing Bella's expression, I thought she must have something in mind.

"Wait." Bella said short and to the point.

"Wait?" Elena was puzzled, "When?"

"It won't be long." Bella replied.

So, the three of them sat in Madame Roland's living room and drank tea.

I sat like this all afternoon.

"Let's go." Just as the sun was about to set, Bella stood up and said.

"Where?" Mrs. Frida asked.

"One more trip to your house." Bella replied.

And just like that, the three of them got in a carriage and returned to Mrs. Frida's house.

"What are you going to do now?" Elena asked, puzzled.

"Didn't Mrs. Frida say before that there were thieves in the house recently?" Bella said.

"Huh?" Mrs. Frida said, "Like...... That's the thing."

"Then we're here now...... "Do you want to catch the thief?"

"Almost." Bella replied.

"But how do you know the thief will come back today?" Elena asked, puzzled.

"Well, if I'm not mistaken, Lady Frida," said Bella, "you'll be able to see your husband soon."

"Huh? Really?" Mrs. Frida said happily.

"I still don't understand." Elena shook her head, "Could that thief be Mr. Frida?" That doesn't make sense, why did he go back to his house secretly?"

"The thief probably won't be Mr. Frida." Bella said, "However, he should take us to meet Mr. Frida."

"Huh?" Elena had a question mark on her face.

"Anyway, I'll wait." Bella said.

Bella, Elena, and Mrs. Frida hid in Mr. Frida's room.

And the lights were not turned on.

Just wait for the rabbit.

At about eight or nine o'clock, there was a sound of footsteps on the stairs.

Listening to the voice, it should be a middle-aged man.

After entering the room, he walked straight to the closet. Then I opened the wardrobe and took out a few pieces of clothing from it.

"Excuse me." Bella said, turning on the lights in the room.