Thank you for all the great reviews. A lot of people were really close to the answer. Just so you know in part of this I had to just kind of make up part if that makes sense. The place is a real place but i added in the thing. Read it and mabe you'll get what i'm trying to say. Also its not the longest chapter in the world so i want you to know there will be more flying your way asap!

"There's nothing here boss. No message from anybody. The guy is a freaking genius." Ryan said fiddling with Beckett's computer.

"Can you remember what it basically said?" Esposito asked.

"I can try. I need a pen. Where is my pen?" She asked searching around her desk.

"Here" Nickels said handing her his.

"Thanks." She took the pen and tried to think. She remembered the North South East West then something about failing. Knowledge in a Dewey way. 4 down to K. As soon as she finished writing it down she knew what it was generally talking about.

"Knowledge in a Dewey way?" Ryan asked looking over her shoulder.

"The Dewey decimal system. It's got something to do with a library."

"But what about the directions?" Esposito asked.

"I'm not sure. Maybe an atlas or a book with a map." She said fiddling with the pen trying to think.

"And what about the four down to K part?" Detective Horen asked.

"What do four and K have in common?" She asked. Then her phone beeped.

P.S. 89

This made no sense to her. Was he writing P.S like you would at the end of a letter or did it mean something too? Then it hit her. She knew where he was talking about. The K and the four were grades kindergarten through fourth. He was talking about an elementary school. But not just any elementary school. P.S. 89.

"It's P.S. 89 elementary school library." She said to her colleges who had been looking at her strangely since she figured it out and her mood changed. She searched for an address. 201 Warren Street, New York, NY.

"Okay so we have that figured out but we still don't know why he put the directions in there. It could be North or South or East or West of the school." Detective Bentley said.

"No, it's not. In this particular library there is a giant world map on the ceiling. It's twenty minutes from here."

"Let's go." Ryan said grabbing his jacket.

As they all walked out Beckett noticed the time. It was 4:00 when they were taken and it was ten minutes to eleven now. They were making good time. But still if the school was another clue that leads to another clue, they only have seventeen hours to rescue Castle and Alexis. Sure they were probably at the school, but if they weren't Beckett felt like she might give up. She knew she wouldn't really but this guy was really good.

So The part i added in was the map. idk if this school has one but i've seen a school that does and it was pretty cool looking so thats why i added it in. Thanks for reading and please review even if you dont like it.