Author's Note: Heeey guys, this is kind of my first attempt at writing a fanfic, so...please be nice to your little collegue here :)) Also, this story is based on a game called "Cause of Death", it actually follows the same line except that, now, we can see our favorite OTP trying to solve the same case. Thanks and enjoy :D

Chapter 1:

Kate opened her eyes just to meet a peaceful snoring Castle by her side; her mornings had been exactly the same as the very first time they slept together, except for the fact that this time she wouldn't have to go hiding as soon as Martha came by the door.

She was lost in her thoughts when a sleepy "Hey" brought her back, "Morning" she answered leaning over to kiss him, it was a sweet and quick kiss but she could still feel the spark and electricity that ran through her body, which made her smile.

-Well, somebody is a morning person. Something happened yerterday?- his blue eyes shinned with curiosity, his writer side showing up again, wanting to know the story behind everything, one of the many things she found adorkable and irresistibly hot at the same time.

-Yes something happened yesterday…- she teased.

-Wait, was it something about that case? Oh I knew it, it was a werewolf wasn't it? Those wounds and the howl…Why didn't you tell me?

Beckett rolled her eyes -Castle, would you let me finish? It was nothing related to the case, what I was trying to say is that yesterday I had…

-Oh I get it, Lanie told you something interesting wasn't it? What was it? Was it about Esposito and her? 'Cause if that's so, I don't think I wanna know. But if it was something about corpses and blood or…

Good… he had lost it again. She could still remember how annoyed she would get when he started blabbering around about some crazy theory or just another featured videogame, usually she would just ignore him and look for evidence at the crime scene but they were in bed now and she had nowhere to run, so she just waited for it to pass naturally.

-or some new toxin that could kill someone in less than 1min but would go totally imperceptible inside the body because of the temperature and…and… you're giving me the look again…I'm going to shut my mouth now…so you can…ahn…talk…about…what were you saying?

-No, no, keep going Castle I don't wanna ruin your moment.

-Hey, no sorry- Castle said putting her hair behind her ear, which made her heart race. 5 years and he could still make her feel like a teenage girl with uncontrolled hormones all over her body -You have all the right to be mad at me, but seriously, now I want to know, yesterday?...

He was raising his eyebrow making everything harder than it already was, god, he really was ruggedly handsome, what even mattered telling him what happened yesterday she just wanted to rip their clothes off right now. Kate was about to speak when her cellphone vibrated, damn, it was Esposito. Beckett answered it, damn 2, another case…by the corner of her eyes she saw a very unhappy puppy dog Richard Castle dying with curiosity.

-Castle, C'mon, we've got a case-Beckett tapped his leg after hanging up and getting out of the bed.

-What, now? But you were about to tell me the- so- mysterious- thing- that- happened- yesterday and I'm shortening it, for now, this thing shall go as TMTTHY… WAIT OOOH NO, NO, IT SHALL GO AS TIMOTHY, IT'S LIKE A SECRET CODE.

The detective was already running around the loft and had stopped listening after "I'm shortening it" what mattered now was the victim, the crime scene and what the hell she was going to wear. She decided to go classic, beige Burberry blazer, basic grey shirt, slacks and of course her high heels.

When she was done, Rick was not even close to dressed; he was like a 5 year old child, who didn't want to go to school, taking hours to just put his pants on. She couldn't complain though, in fact, the now teenage-with-hormones-beckett took that moment to admire her boyfriend, his muscular chest and arms, his scruffy hair, his lips, his deep blue eyes. Their eyes met and Castle couldn't resist those green brownish eyes checking him out, he walked towards her, pulled her closer and they started kissing, gentle at first but even Beckett gave up and responded with equal passion and savagery, their tongues trying to capture each other's sweet taste. Kate's mind was racing and before her conscious side could make her stop, her hands were already running through Castle's hair and body. His lips had, now, encountered her collarbone and, slowly, made all their way back to her mouth where they shared one last long kiss and pulled each other apart with kindness, both breathless but with silly smiles on their faces.

When they arrived at the crime scene, everybody was already there. They walked through the dead end and Kate noticed that there was no trace of blood assuming that maybe the victim was killed in another place or the killer was one of the murder-and-clean type. They crossed the yellow strip just to find Esposito and Ryan waiting for them.

-Good morning ya all, you guys are late again- Esposito bullied

-Well detective Esposito, do you really want to know, because I could…- before Castle could finish, Kate cut him off.

-Yeah, ok, Castle. So what do we have here?

Ryan consulted his little notebook and answered – The victim's name is Sofia Miller, she's 24 according to her driver's license and was found by Claire Stiles at 1:00am, when she was taking the trash out.

-And what about the murder weapon?- Castle inquired, Beckett was wondering the same thing, but she knew that he would ask that, how did she know that? It was still a mystery but it worked just fine to her.

-We tried to look inside the dumpster again, but CSU found nothing, now they're just looking for evidence but looks like this one is a tough one. Hey Lanie- Esposito said winking at her and flexing his muscles, which she chose to ignore, but it still made her blush a little.

-She has no signs of struggle, only a little pinch on her neck which I'll be able to examine at the lab along with…this…-the forensic analyst said pulling back the black sheet that was covering the cadaver so the pair could take a look.

As she did so, a sudden shiver went down through Kate's spine, she had seen many corpses before, but this one was different, where there should be Sofia's face, laid only a heavy white plaster mask, which the killer probably used to suffocate her. Beckett's mind was working again, trying to connect the dots, her eyebrows frowning like they always did when she was thinking too hard about something. Her concentration, however, was broken when Castle shouted:

-No way! I know this work, this one's easy. I already know who the killer is.

The team turned their heads in synch with an interrogation look on their faces.

-Care to share the information, Castle? - Beckett asked, more like demanded, she hated when their connection was off.

-You guys don't know? It has to be the Maskmaker, look at her, casually dressed, 20-30 year old woman AND the most obvious of the evidences, she's wearing a white mask.

Ryan nodded all the time but then realized that he didn't really get it, who was the Maskmaker? He'd never heard of him before. As he looked to his colleagues he saw that he was not the only one, they didn't get it either. Esposito took courage and asked one more time:

-Sorry to ruin your moment of epiphany Castle, but we don't know who the guy is. Maybe if you tell us his name…

-That's the point! He doesn't have a name because he was never caught. From what I know, this guy has killed 8 girls before, all of them were young and beautiful and all of them were left with only a…white….mask….

-Ms. Parish, the ambulance is ready to take the victim to the Precinct- a tall young man with copper hair said out of nowhere, making Esposito jump.

-Thank you, Sam. Oh I totally forgot, guys, this is Sam Travis, he's my new intern and will be assisting me on this case.

-Well then, let's go back to the precinct; maybe there we'll be able to find new information. – Beckett couldn't stand being there any further, the lack of evidence was driving her crazy and the fact that Castle and his theories were the only useful source of the killer's background history, didn't quite help her think straight.