This is my first crossover, hope you like it

Chapter one: To Ohio

Kate Beckett sat behind her desk. It was a normal day, without a case. Okay may be a day without isn't a normal day? Castle had gone home to work on his book and Ryan and Esposito were having lunch when the captain called her into his office.

"Beckett," the captain said.

"Yes, sir."

"In my office." She walked in. His tone was serious, it made her nervous.

"What's wrong, sir?"

"Sit down." She sat and he continued.

"I think I have a case for you, but it's a case that's going to take much from you and I want to know if you want to do it."

"What's the case?"

"We're chasing a serial killer. He escaped from jail, a long time ago, and was untraceable, until a few days ago."

"Where is he?" she asked.

"Ohio," he answered.

"Ohio? What has a serial killer to do in Ohio?"

"I don't know. We only know is that he is a concierge at a school, the William McKinley High School, we think he may be there because he has found his next victim."

"How does a serial killer get a job at a high school?"

"He changed his name, he changed his face. He changed everything." The captain showed her two pictures; they were of two very different people.

"And you're sure it's him, sir?"

"Positive."

"So what do I have to do with it?" Now was Kate curious of why she was told about a case in Ohio?

"We want you to go undercover and find him before he kills someone else."

"Okay, but why me and not an Ohio detective?"

"Everyone knows every cop there, so if one of them goes the students and teachers will know that something is wrong."

"Alright."

"So, do you want to do it?"

"Of course, I will do everything I can to find him." She didn't like to go away but she knew it was an special opportunity. She wanted to help the city she loved. Why not the country to? She had to do it for the people in Ohio

"I'm sure of that." He nodded to her.

"So what is my cover?"

"Math teacher."

"Okay, I think I can do that." When Kate was in high school her favourite class was math. She was really good in it. She helped her friends always with it.

"Good. You'll have your own place and everything waiting for you."

"Great."

"Do you think that you can leave tomorrow?" he asked

"Yeah, I think so. I will get packed and tell my dad and come along tomorrow morning for the last pieces of information."

"Okay, good. I'm glad you want to do it/"

"Of course, sir, will you inform the others, except Lanie, I'll go tell her myself."

"Of course." With that Kate walked out of his office and to the morgue.

Kate walked into the morgue and Lanie looked up from some paper work she was doing. "Hey girl! What are you doing here? You know I don't have any dead bodies for you today" Lanie said.

"I know, but I have to tell you something".

"What's up?"

"I'm going away for awhile"

"Go like, gone?" Kate nodded. "Where?" She asked again

"Ohio."

"Ohio? What are you going to do there?"

"Working at a school."

"What is this about? You have work here."

"I know. It's for a case. There's a serial killer escaped from jail and is now a concierge at that school and I have to catch him."

"They have cops there, why can't they do it?"

"Because then the children will know that something is wrong, they know every cop in town."

"When do you leave?"

"Tomorrow."

"Wow! That's fast!"

"I know, but if it takes too long, you can visit sometime, maybe?"

"I will, for sure," Lanie said.

"So how does Castle feel about you going on this case?" Lanie said.

"I haven't told him." Lanie raised an eyebrow at her. "What? I only just got the case myself."

"So you came all the way down here to tell me first?"

"Yeah?"

Lanie shooked her head at Kate. "I feel very honored, Girl. But that man is your partner, don't you think he gets a little more priority than I do?"

"Yeah, well, I don't think I could tell him myself."

Lanie sighed and the conversation was dropped.

"I leave tomorrow morning to the precinct, maybe you can come to and say goodbye?" Kate said.

"I'll be there."

Kate smiled, it was hard to go, but she knew she had to.

Kate drove home. The first thing she did was call her dad. She had a hard time explaining it, but he understood and would come along the next morning to say goodbye. She had told Lanie and her dad, but it was weird. She didn't know when she would come back. She hoped that Ryan, Esposito and Castle would take it well. When Kate had packed and eaten, she went to bed.

The next morning Kate woke up around nine. She had her morning coffee when her dad came in. He was the only one who, besides her, had a key for her apartment. Together, they put everything in her car. Now she was ready to go.

"Bye dad," she said and gave him a hug.

"Bye Katie and be careful." She felt like she was eight again, he always said that.

"I will dad, and I'll call you." He gave her a kiss on her head and they let go of each other. Kate stepped in her car and drove to the precinct.

Everyone was there and looked to her. She knew that the captain had told everyone. She greeted Ryan, Esposito and Castle like it was a normal day. She didn't walk to her desk as usual, but walked to the captain's office. "Sir, I'm ready to go."

"Okay good. Here, it's you new home" He gave her a route description and keys. "I know it's not forever but it's going to be your home for a while. The school is five minutes from your new house."

"Okay, thanks."

"You will be received by the guidance counsellor, tomorrow, and you'll start teaching Monday, until then you will be with the guidance counsellor; her name is Emma and she will show you around."

"Alright."

He nodded and gave her a hand. "Bye, Kate, I hope I see you soon."

"Me too."

She walked out of his office and saw the three boys, her three boys, looking at her.

She stood in front of them. She didn't really want to say goodbye, because she knew it wasn't forever. "You really going?" Castle asked.

"Yeah, but it isn't forever, Castle, I'm gonna catch this guy."

"But you also don't know when you'll be coming back."

"That's true, but we'll keep in touch."

"We will." They shook hands.

"We're gonna miss you," Esposito said

"I'm going to miss you guys too."

There was a silence.

"Don't solve too many cases without me," she sarcastically. "If you guys can"

"Ha ha, very funny" Ryan said "But we won't"

"and we'll let the creepy ones wait for you," Esposito said, they where laughing.

There was again a silence.

"It looks like you guys think that I am going to leave forever, but I will be back soon. Maybe you won't even know that I'm gone"

"How can we not know that our boss is gone?" Ryan asked

"Okay, maybe you will but you can always come along if you miss me. I have a whole house!"

"We'll come soon." Esposito said

"Good."

They hugged and she walked to her car. Everyone walked with her. Lanie had joined them. Kate gave

Lanie a hug and stepped into her car. She waved her goodbyes and went to Ohio. A nine hour trip, to her case. Am I really going to do this? she asked herself. Yes, you are, she answered in her head.