At Agreste Castle, Nathalie was in Y/N's bedroom where she was showing them pictures on the tablet. The pictures showed them taking the book from the safe.
"Why did you take the book?" Gabriel asked, standing with his back to them. The two of them sat on the sofa while they looked at each other worriedly. "We-We just wanted to know what you were hiding behind that portrait that was so important. You...You never told us about those things." Y/N started.
"We were intending to give it back to you, we swear. But then...we lost it." Adrien continued. They bowed their heads in guilt. "How can I possibly trust you again, Y/N and Adrien?" Gabriel asked, his face still deadly calm.
"Sorry. We'll get you another copy." Adrien said, but then Gabriel growled. "It's one of a kind! The book's the source of my inspiration." his hands clasped behind his back. The two looked at him in fear. "We didn't know that." Adrien lamented.
"We hardly know anything about you, Father. Maybe you could open up to us a little sometimes." Y/N said as she said the last sentence a bit softly.
"You won't be returning to school. You'll be home-schooled again, with Nathalie." They gasped at that statement. They didn't even have time to protest, as the two adults had already left the bedroom.
They sat in silence for a moment until Y/N spoke. "It's my fault. I shouldn't have just taken the book. Now we're in trouble because of me. I'm so sorry." she said as she put her head in her hands. Adrien looked at her sadly, then moved closer to her and took her hands from her face.
"Hey, it's okay. You couldn't know. I was in on it anyway. I was interested in the book too. Honestly, he couldn't blame us. He's hiding a lot and it's understandable if we're curious. So please don't blame yourself. We'll find a solution to this, I promise." he comforted her.
She smiled faintly and hugged him. He happily hugged her back.
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After a few minutes, Adrien went back to his own room. Y/N started playing with the foosball and was thinking. Plagg was looking at her a little pityingly, so he decided to try to cheer her up a bit.
"Well, look on the bright side. Your father could have found out about me. It's a good think we kwamis can never be filmed or photographed. Ah, those photographers have no idea what they're missing."
"We've gotta find that book, or we'll never be allowed to return to school." she explained as Plagg flew to her side in disbelief. "Return to school? Are you crazy? No more homework, no more alarm clocks. We should be celebrating! Hey, I know." he flew away and returned with a bottle containing a piece of cheese.
"I named this piece El Plaggo. It's been maturing for 999 days." he explained with satisfaction as Y/N looked at it in disgust. Then they started hearing sounds that sounded like someone smashing something. She quickly ran out the door of the room.
As she came out of the room, she saw that Adrien had also come out, then they looked at each other for a moment and ran down to the office where the voices came from. Their bodyguard followed them closely. Nathalie stood in front of the door and held out her hand to stop them.
"Your father is very busy. Shouldn't you two be practicing the piano right now?" They were saddened as the bodyguard escorted them back to their room.
When Y/N got back to the room she put her phone on the music player and started some music. She grabbed a remote control and pressed a button that opened one of the windows.
"My father's angry because of us. He won't forgive us until we find that book. So now I'll go and find it." Plagg flew in front of her in protest. "May I remind you that you're actually grounded?"
"Y/N is, but Kitty Noir isn't." she grinned at him. "Plagg, claws out!"
She jumped up to the window, but before she could jump out her staff signaled that a message had been received. She pressed the play button and the message started. "Kitty Noir, I think I know who Hawk Moth is. Get your whiskers over here, fast!" She was surprised to hear this.
"Wow. I guess the spellbook will have to wait a bit longer." she said, then headed to the meeting place. She jumped from rooftop to rooftop until she finally reached the roof of Francoise Dupont. Smiling, she walked over to her partner, who looked a little impatient.
"Kitty Noir, did you get my messages?" Kitty Noir twirled her staff, then leaned on it and stared at her with a grin. "Yeah, and I can't wait to know more, M'Lady-tective. So, who's the suspect?"
"Gabriel Agreste." she gasped and her eyes widened. She lost her balance a little, but quickly regained her composure. Ladybug was a little worried about her reaction, but then continued to speak. "You know, the fashion designer?"
Kitty Noir turned away from her slightly as she processed the information. "You got proof?" Ladybug was a little surprised. "Uh, um...I can't tell you."
"So, I'm supposed to just accept that?" she was in disbelief. "You must trust me on this. But it all makes sense. Gabriel Agreste is a secretive man, and he never leaves his house. And get this." she said then showed her a magazine on the yo-yo with Y/N on it. "Check out his brand's logo."
She zoomed in on her shoe, which had a butterfly mark on it. "A butterfly?" Kitty Noir's eyes widened again as she remembered a few things. The butterfly sign appeared in many places in her home. For example, on the pattern of the floor or on the side of a flower pot. The more she thought about it, the more it made sense. She was getting more and more worried.
True, her father was a mysterious and cold-hearted man. But could he really do that? Her thoughts were interrupted by Ladybug, who saw the concern on her partner's face and put her hand on her shoulder. "Are you okay, kitty?" She turned away from her and stared straight ahead.
"It's time to get to the bottom of this." she said, then jumped off and headed towards Agreste Castle. Ladybug followed her closely.
Unbeknownst to us, a figure was behind a statue listening to them leave. "My plan is working perfectly."
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After a while, they reached the castle and then entered the office. They looked around and saw broken statues and ruined pictures of the twins on the floor. "Whoa, what happened here?" wondered Ladybug. "Looks like somebody had a little tantrum."
Kitty Noir walked over to a small framed picture on the floor. The picture was more precisely a drawing that she and Adrien made when they were young. It was her, Adrien, Gabriel and her mother Emilie holding hands.
A terrible feeling came over her as she looked at the broken image. Of all the broken things there, this bothered her the most. That was what really hurt her.
Ladybug walked beside her and was still worried about her. "Are you sure you're okay?" she asked, then she also looked at the drawing. "Yeah. Yeah, let's keep going." Then the blue haired gasped. "He's got children! Let's go check their room, make sure nothing's happened to them." they ran out of the room, but then they noticed someone at the top of the stairs. "Where's Gabriel Agreste?"
"There is no more Gabriel Agreste. There is only The Collector!" he said, then threw his book at Ladybug, who quickly jumped over, causing it to hit the door and absorb it. The book flew back into his hand. "You won't be able to escape!"
He started throwing his book, which the heroines dodged and tried to fight him. They kept avoiding the book and then ran into the dining room. Kitty Noir threw her staff at him, but he blocked it with the book, which absorbed it. "Nice piece, wouldn't you agree?"
The blonde threw a chair at him, which he also blocked with the book. While he was busy erasing the drawing of the chair from the book, they ran away. They hid behind the stairs.
"The akuma's gotta be in that book." said Ladybug. "Yeah, but if we touch it, we'll disappear." Kitty Noir explained. The blue haired smiled and then took out the yo-yo.
"Lucky Charm!" A pedal appeared from it. "Uh, a pedal?" She looked around but saw nothing. "I have no idea what to do with this. We need to stall him." Then the stairs disappeared behind them.
"Ladybug and Kitty Noir, you shall be the masterpieces in my new book of inspiration." He threw the book at them, which they quickly dodged. Kitty Noir attacked him, but he kept trying to touch her with the book. She dodged him until she backed up to the wall, but he couldn't touch her as Ladybug held his hand back with the yo-yo.
They both attacked him, but he dodged their blows. Kitty Noir kicked the book out of his hand and tried to hit him, but he hit her. He jumped up for the book but couldn't catch it as Ladybug pulled him to the ground with the yo-yo. He reached out for the book, which caused it to slide into his hand.
He touched the yo-yo so it absorbed it too. "My collection's growing." He threw it at her, which she jumped over and rushed over to Kitty Noir. The book went towards them, so they jumped upstairs.
"So, that must mean...Gabriel Agreste can't possibly be Hawk Moth, since he's been akumatized." the blonde explained, feeling relieved. "You call Agreste turning into The Collector good news?" The barrier in front of them disappeared, so they ran again.
They ran into Adrien's room and blocked the door. "Gabriel Agreste's daughter and son aren't at home?" asked the blue haired. Kitty Noir wondered where Adrien might be and began to worry. "Do you think he caught them?" she asked, hoping that wasn't the answer. "Would he be able to do that?" worried the bug hero.
"Adrien? Are you here somewhere?" the blonde shouted, hoping to hear an answer. There was silence for a few seconds, but then the bathroom door opened. "Kitty Noir? Ladybug?" he was surprised but felt relieved. Kitty Noir also felt a sense of relief. She was glad he didn't catch him.
"Are you okay? Are you hurt?" asked Ladybug. The boy shook his head in response. "No, don't worry, I'm fine. But I can't find my sister Y/N. I'm worried that father caught her." he said, causing Kitty Noir to tense up a bit. "Don't worry. Even if he did, Ladybug's magic will bring her back. But until then, hide back there." She told.
Adrien was about to say something when they heard voices coming from the door. The Collector had just removed the barricades from the door. The boy looked at it scared, but then quickly hid back in the bathroom. The two heroines were now watching the door. "You cannot escape from me!"
"What if he has no pages left in his book?" the blue haired wondered, then looked around and saw a bunch of CDs. She quickly ducked behind the TV while Kitty Noir jumped up to the records.
"But before I immortalize you, allow me to seize your Miraculous for Hawk Moth." he said, then she called out to her partner. "Kitty Noir, I need immunity!" She quickly ran away as the villain threw the book at her.
The cat hero looked up at the CDs and then smiled. "You are clever, M'Lady." Ladybug jumped up to her, then took off her belt and hurried to the foosball table. The blonde dodged the Collector's punches then throwing him on the floor. "Cataclysm!"
She crushed the CD shelf so they fell off. "Ready, my kitty?" she called out to her as she assembled a machine. "I'm always ready for you, M'Lady!" Kitty Noir started dropping the CDs as Ladybug wound the machine so it shot them at the villain.
He kept fending them off with his book until he finally got to the foosball. He also absorbed it, but when he tried to touch the heroine, nothing happened. He looked at it in confusion, then saw that his book was full. He wanted to erase a CD, but Ladybug kicked it out of his hand.
Kitty Noir caught it and then tossed it back to her partner, who quickly cut it. "My book! No!" The akuma flew out of it.
She grabbed the pedal and threw it into the sky. "Miraculous Ladybug!" The spell brought back all the buildings and people and repaired the damage to the house. The heroines' weapons are also back.
"No more evil doing for you little akuma. Time to de-evilize! Gotcha! Bye bye little butterfly!" The purified butterfly flew away and The Collector transformed back into Gabriel. Kitty Noir looked at him worriedly, but before she could go to him, the bathroom door opened and Adrien came out. He saw his father and quickly ran to him.
"Father! Are you alright?" Gabriel held his head in pain, but then looked up at him and smiled in relief. He then looked at the two heroines. "Kitty Noir, Ladybug, what happened to me?" Kitty Noir came closer to him and crouched down to his level.
"You were akumatized by Hawk Moth. But don't worry, it's over now." she explained. "Thank you. Thank you, both of you." He stood up and turned to Adrien. "Are you okay, son? I hope I didn't do anything wrong to you and Y/N." Then he realized something.
"Y/N? Where is Y/N?!" he exclaimed, then ran to the bathroom to see if she was there, but she wasn't. "She must be hiding." came the blonde's voice.
"Kitty Noir is right. Otherwise, your daughter would have reappeared right here." assured Ladybug. "Nothing must happen to her. She's too precious to me." Kitty Noir listened to him with a smile. She was glad that her father cared about her. Then the beeping of their miraculous rang out.
"We're about to transform back. Goodbye, Mr. Agreste." the blue haired said as she walked towards the window. "Don't worry yourself, sir. I'm sure your daughter is safe and sound." the blonde said, then followed her partner. Adrien waved to them while Gabriel watched them leave with a wicked smile.
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A few hours after what happened, Y/N and Adrien were called into the office by their father.
"I'm sorry I became so furious over a book." he said as he put it back in the safe. "We shouldn't have taken it without your permission." said the boy.
"That book was the very last gift your mother gave to me before...before she disappeared. All I have left of her is this book and you two. But I know I can't keep the book or you two locked up in this house forever." he explained as he walked over to them.
"Does that mean you'll let us go back to school, then?" Y/N asked. Gabriel nodded to them. "Thank you, Father!" they said at the same time, then hugged him. And he hugged them back.
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The next day, a familiar car appeared at the school entrance. The twins got out of the car and Nino immediately ran to them and hugged them. Then Chloé pulled him away from them and threw herself at them. Adrien gave her a slightly nervous smile while Y/N was genuinely happy for her. She kind of missed her and her cocky attitude.
Soon other students from the class came to them.
At the door of the school, Marinette watched the scene with a smile, and Alya put her hands on her shoulders happily.