The sharp, shrill tones of a cell phone cut through the air, rousing Castle from his sleep. He groaned, rolled over and looked at the clock: it was half past midnight. Rubbing his eyes, he threw the covers off of him and rolled out of bed, stumbling and tripping over some unidentified object in the dark.

"Dammit!" he hissed quietly, grabbing his foot and hopping around a bit as he tried to find his phone. Finally, he turned on the lights, found the phone lying innocently on the nightstand next to his bed, and answered it.

"Castle." he said, the sleep still evident in his voice.

On the other end of the line, Detective Beckett tried to hide the smile that had somehow crept onto her face. He sounded just like a little boy, up past his bed time. As much as she liked to complain about how his childish traits annoyed her, secretly, she found them a bit endearing.

"We have a case." Through the haze of grogginess that impeded his thoughts, Castle thought he could detect a hint of unease in Beckett's voice.

"Is everything alright?" he asked, concerned. Beckett wasn't the type to get worked up over a dead body, considering the nature of her work.

"Yeah, Castle, just-it's bad. And strange, very strange. Just..get down here." She gave him the address of an apartment building not too far from his own.

"On my way."

Castle stepped out of the elevator, smelling the ghastly scent of death as soon as he started walking down the hallway towards the victim's apartment. Castle could never mistake the smell of decaying bodies for anything else. It was like rotting garbage, or meat that had been left out of the fridge for too long, only much worse-because the victim was a person, not garbage, and not rotten meat. Taking a moment to compose himself, Castle took a sip of his coffee and wished that the smell of coffee beans was strong enough to overpower the tangy, metallic scent of blood that hung in the air. Normally, such a moment was unneeded, but there was an aura of fear that, like the smell of blood, hovered in the air like a thick fog. Suddenly, he was reminded of old cartoons where a grumpy character would be followed around by a rain cloud.

He ran into Ryan and Esposito in the doorway of the apartment. They were deep in conversation, their faces uncharacteristically grave.

"So...who's our vic?" Castle asked casually. He had thought about inserting a joke to alleviate the tension that filtered through the air, but thought better of it. He got the impression that this wasn't a case to make light of.

"Vic? You mean vics. There are seven people dead in there, Castle," said Esposito as he moved out of the way, allowing Castle to enter the apartment. However, Castle didn't move, being too preoccupied with choking on his coffee.

"Seven? Seven?! That's not a murder-that's a massacre!" Castle shouldered past the two detectives in an effort to see for himself. He just couldn't believe it. Seven people dead? That was insane!

"Castle, wait." Ryan stopped him with a hand on his shoulder, and Castle turned to face him, noting the look of disgust that came over his face.

"I feel like I should warn you, before you see for yourself," Ryan hesitated and took a deep breath. "The bodies are in a bad way. They've been torn apart. Part of the skin's been removed and..." Ryan lowered his voice to a whisper, "They've been cannibalized."

Castle ran his hand through his hair, eyes wide, feeling a bit sick. He looked at the two detectives and gave what was intended to be a grateful smile, but it came out more like a grimace. Then he entered the room.

The first thing he saw, as always, was Beckett. In any room, in any light, and in any situation, his eyes always seemed to be drawn to her before anything else. She was walking around the room, observing the crime scene with a frown, her brow furrowed. His eyes followed her gaze.

Then he saw the bodies.

Castle has seen many terrible things in the years he had worked with the NYPD. Bodies had been stuffed in freezers. Innocent people had been killed because their loved ones had involved themselves with the wrong people.

Children had been murdered.

But nothing compared to this.

A dark-haired young man, perhaps in his mid- to late-twenties, was sprawled over the couch, with half his face torn off, clothes in tatters. The man was covered in dozens of small wounds, and chunks of his flesh was missing. Another body-Castle thought it was a woman, but couldn't be sure-was hunched up near the man's, a chunk of her neck missing. Were those bite marks? Castle started to walk forward, but blanched when he spotted a child's finger on the floor.

He dropped the coffee, both his and Beckett's, and it was only thanks to the lids on the thermoses that the coffee didn't spill over the floor and contaminate the crime scene.

[1] "Shun-SHENG duh gao-WAHN!" Castle muttered quietly under his breath. Thankfully, nobody heard his random Chinese expletive. He had learned tidbits of the language long ago, from a TV show he used to love, but it still wasn't as though he threw Chinese words into his conversation or anything.

Beckett looked up at the sound of the thermoses hitting the ground.

"Castle! You're here!" she said, watching as he gathered up the coffee and then handed over hers with a brief, sheepish smile that faded quickly as he looked around the room. Beckett caught his expression. She sighed.

"I've seen a lot of horrible things as a police officer, but I think this tops them all. I mean God, Castle. They even killed the children!"

"It's just...so senseless. Who could do something like this?" he asked quietly.

"I think I can answer that question."

Castle and Beckett both jumped, not having heard Esposito come up behind them.

"Have you been in the bedroom yet?" he asked. Beckett shook her head.

"Hadn't gotten to it yet."

Esposito raised an eyebrow. "We found a man with a gun, and another riddled with holes. We think that the man who was shot may have been the murderer." Beckett and Castle gave each other a look, and then followed him into the bedroom of the apartment.

There were gasps all around as they entered the room.

There were two men in the room, and from the looks of things, it appeared that one man had shot the other, and then turned the gun on himself. The first man was wearing jeans and flannel-he had a sort of Southern look to him, aided by the shotgun held limply in his hands. The other was...monstrous. He had a wild look to him, like a caveman. His hair was long and untamed, matted and dirty. His skin was peeling off in some places, and it appeared that metal had been stabbed into his face somehow. He had been shot several times in the chest, presumably by the man with the shot gun. The sight of the wild man with the crazy hair, the unkempt clothes, and the skinless face was just unsettling.

"What happened here?!"

That night, Castle dreamed of cannibals and spaceships.

"...Reavers," he whispered into the night, and suddenly wondered what he had gotten himself into.

A/N: Please refrain from throwing rotten tomatoes! It's been years since I've written anything at all, and I've never written anything for Castle or Firefly. In fact, everything I've written in the past is something of an old shame-the only reason I haven't taken all my old stories down is because I know I hate when writers take stories down. I'm very rusty, I'm sure, so constructive criticism is welcome. In addition, if anybody would like to volunteer to beta this for me, I'd greatly appreciate it.

Please be kind, folks, but don't be afraid to tell me if it's awful and I've forgotten everything about writing a fan fiction.

[1] Holy Testicle Tuesday!