Castle sipped his coffee. It was late, though he had decided to stay at the precinct and help out with whatever he could. He didn't have to go home to his mother or Alexis. It was going to be a long night. Kate was sitting at Jane's desk, the desk she used when the brunette wasn't there. She really should be getting some sleep, because she was taking up post at the Byrne house at 6 am with Barry Frost. Just then, a delivery man walked into the bullpen.

"Delivery for… Kate Beckett?"

"Here." Kate lazily signed for the package and set it on the desk. She watched through drowsy eyes as the man left. She tore at the tape and removed the bubble wrap.

"Castle."

"Hmmmm…?"

"I… This is a severed hand." Castle was by his partner's side by the time she had finished saying severed. They both stared down at the hand, which was surprisingly clean. There was a wedding ring on it, though it was hard to determine whether the hand was the right or left one. The hand was otherwise unidentifiable without a DNA analysis.

Castle was astounded. "Interesting."

"I need to find that delivery man." Kate ran to the elevator with Castle on her heels.

Frost walked into the bullpen and was drawn to the box on Jane's desk. He had been at the Dirty Robber with Esposito and Ryan, striking up a friendship. He lifted the box's lid and almost gagged. He was never well mannered around the gory stuff. He looked around for Castle or Beckett, but they were nowhere to be found.

Frost coughed. "Guys, I'll take this down to Dr. Isles."

Detective Ryan poked his head over Barry's shoulder. "What is it?"

"A severed hand." After exclaiming about how gross it was, the three detectives ventured down into the morgue, but found Maura absent. Frost pulled out his phone. "I guess I'll have to call her."

Maura arrived ten minutes after Barry's call, only applying another set of make-up to cover that fact that she'd been crying. She was greeted in the morgue by the three detectives crowded around a small box. As she neared it, she saw a flash of decomposing flesh.

"What is this?" She put on some gloves and pulled out the hand, causing Frost to turn a slight greenish color.

"It was mailed to Beckett."

"This is Mrs. Byrne's ring."

Frost looked confused. "How do you know?"

"I asked her about it. It's a beautiful wedding band." Maura started examining the hand. "The cut is very clean… It looks almost professionally done. It's only been off a couple of hours, it's still quite warm."

"Does this mean she's dead?"

Maura shook her head. "We have to assume she's still alive. This certainly isn't enough blood loss to die."

Castle noticed the room was dark when he awoke. There was a pounding in his head and a weight on his chest that seemed to constrict his breathing. The weight moved slightly and groaned. It was Kate. The writer's hands were tied behind his back and Beckett's arms were tied around him. Kate groaned again and tried moving more forcefully.

"Stop, Kate."

"Castle?"

"We're tied together."

Kate shifted slightly, careful not to put any excess weight onto her partner. She tried pulling at the restraints, which didn't budge. "We should try to get up."

"I think that's a lost cause."

"Get on your side, Castle." The two shifted so Beckett could freely move her arms. Her fingers found their way to Castle's hands, and untied his restraints without much difficulty. "Untie me, now."

Castle did as he was told and soon the two of them were both standing. Kate found the wall and started shuffling through the dark. She had already checked for her gun and found it gone.

"Castle, this way."

The writer stumbled towards the general direction of her voice. "Coming!"

The two inched along the wall in complete darkness, but soon Kate noticed a slight glow coming from in front of them.

Castle was grumbling. "My head hurts. Where do you suppose we are?"

"I have no idea… There's a light up ahead."

The writer squinted his eyes. "Looks like a greenish glow. Oooh! What if we were abducted by aliens?"

Kate didn't bother egging him on. He head was reeling. She was trying to recall the last thing she could remember before she blacked out. She remembered following the delivery truck to an abandoned warehouse. She looked above her head, squinting, trying to see past the darkness. She didn't feel constricted, so the ceiling must've been high. She wanted to yell out, to see if there was an echo, but she didn't want their position compromised.

As the two rounded the corner, the ground sloped down slightly. There were green lights on underneath salt water. There was a drop off a few feet into the water.

"Scratch the alien idea," Castle said.

The water had small waves lapping at the two people's feet. Something triangular broke the surface and came towards them. The two flinched back as a shark cam swimming towards them.

Author's Note: Hope you like it :)