When Castle got to the precinct with coffees in tow, he found Beckett sitting at her desk, completely focused on her computer, River lounging on a chair behind her. The detective looked up with a grateful smile as Castle handed her the coffee. "Thanks." Castle noticed that River's knowing smirk grew as she witnessed the exchange.

Beckett finished off what she was typing and stood. "We're meeting in the morgue," she told Castle quietly. He understood what she was saying; they needed somewhere to theorize where they wouldn't be overheard, and the morgue would provide that. With a nod he followed Beckett and River to the elevator.

As the elevator doors closed behind them, Castle asked his partner quietly, "What are we telling Gates?"

In the same quiet voice Beckett answered, "That we've brought in Detective Cage and Dr. John Smith to consult and we're hitting dead ends. She's not happy, but it's giving us room to work until we solve it."

The partners shared a long glance as each wondered the same thing. Once the case is solved, will there be someone we can arrest, or an invasion to stop?

SCENEBREAK

Esposito, Ryan, and the Doctor were already there and working when Castle, Beckett, and River arrived. Beckett slung her jacket over a chair, frowning slightly when she took in the sight of the morgue. "Where's Lanie?" she asked the detectives.

"Bathroom," Ryan answered, not looking up from the laptop he, Esposito, and the Doctor were looking at. The Time Lord was seated in front of it, typing things in rapidly and scanning with his sonic screwdriver.

Esposito said in a gruffly awed tone, "We're scanning through files of anyone who's been brought in for arrest in the last three days. Dude's fast with computers." He cast a quick glance at the Doctor, who was dead focused on his work. "Still haven't found anything though."

Just then, Lanie came back in, eyes narrowed when she noticed the newcomers. "Hey Beckett, can you keep your alien here on a leash? I don't need him trying to touch everything in this lab." She shot Castle a glare and added, "He's worse than you!"

Beckett rolled her eyes, but River appeared to be biting back a chuckle. "What did you do this time, sweetie?" She asked with amusement.

Without looking up the Doctor answered a little sulkily, "I was just looking."

Lanie's glare shifted to River, though it was more exasperated by this point than angry. "Can you keep your boyfriend here from messing up any of my equipment please?"

River laughed, seating herself in one of the chairs that had been set up. "It's husband, actually," she said with a smirk at Lanie, Beckett, and Castle's surprised expressions, "and I can't promise anything. For a thousand-year-old Time Lord, he can act like such a child sometimes."

The medical examiner replied drily, "Sounds like someone I know." She shot Castle another quick glare before getting a seat herself. "So what are we doing exactly?"

"Looking for anyone with a file and identity that's been faked with alien technology," Ryan answered, still sounding slightly shocked at what he was saying. "The Doctor's looking through files while we try to figure out what's the most logical thing the alien would have done."

Lanie nodded thoughtfully. "Well whatever your killer is, he'd have to worry about hiding the murder weapon," she pointed out.

"Tanya said it's a sword," River recalled, "So it'd be pretty big and bulky."

"Something like that wouldn't be easy to discard, it'd be too noticeable," Castle added. "Big shiny sword, glowing from the heat. If the Fatorin left the scene quickly like we thought, he couldn't have had time to find a proper hiding place for it. He must have taken it with him."

Beckett nodded thoughtfully. "So if he took it with him, he'd have to keep it hidden and keep out of sight. A sword isn't something you can just hide under your coat. So he'd have to stay where people couldn't see him."

"Unless he had a car," Ryan pointed out, causing Beckett to groan with frustration. That put them right back to square one.

"Wait a minute," Castle said slowly. "A car. What if he had a car?"

Beckett shot her partner a confused side glance. "We just said that Castle."

"No, I mean it. What if he had a car? If he did, he would have had to steal it." He hurried over to the computer the detectives and the Doctor were huddled around. "You guys were looking at security footage right outside the garage, right?"

Esposito nodded, understanding suddenly flashing in his eyes. "If it's stolen, we can see if the plates match with a car that was reported missing," he realized aloud.

The Doctor minimized the files he was reading and pulled up the security footage. He fast forwarded through the footage, only pausing occasionally at a screen-shot on the plates of each car passing through. On a separate application he used his sonic screwdriver to scan through stolen car reports with dizzying speed. After few minutes, he paused the footage, snapping the head of the screwdriver back into place. "And there it is!" He pulled up the last file he'd been looking at. "A stolen red Honda Civic with plates ETU 835." He pointed at the paused footage, where the first few numbers of the plates could be made out. "That's the one."

"Nice find," Beckett said, coming to stand behind the laptop as well. "Alright Doctor, see if you can track it's progress with traffic cams and find out where it went."

The Doctor nodded confidently. "I'll have an address in a few minutes," he promised with a smug grin.

River rolled her eyes. "You think you're so clever."

"Yeah, and so do you," the Doctor fired back with a cheeky grin.

River shook her head. "I hate you sometimes."

The Doctor just chuckled. "No you don't."

Beckett looked from spouse to spouse for a moment before shaking her head and moving on. "Once we have an address, we'll all head over." She paused as she noticed how Castle, Esposito, and Ryan were staring in awe at the laptop and the Doctor. "What is it?"

Without moving his gaze, Castle asked in an awed tone, "Can we get one of those?" He pointed at the sonic screwdriver with reverence. Beside him Esposito and Ryan nodded fervently.

Beckett shared an exasperated look with River and Lanie. Boys and their toys. Aloud she just said, "Just let the Doctor work, guys."

SCENEBREAK

A few hours later saw them pulling up to an abandoned warehouse not far outside the city. The area around it was fairly barren, giving the warehouse a wholly deserted feel. A perfect hiding place for an alien far from home.

Beckett shared a wary glance with Ryan and Esposito as they all headed quietly towards the building. All three cops and River were armed, but with only four guns against unknown odds, Beckett didn't like their chances. But they had no choice.

The door was locked, but the sonic screwdriver quickly fixed that. Silently the cops filed into the building, followed first by River, then by the unarmed Doctor and Castle. The Doctor still seemed a little put out that they had brought guns with them, but as Beckett had pointed out, the alien had already murdered someone and was likely to be dangerous. He seemed to have only relented about the guns because Beckett, Ryan, and Esposito were trained cops who would only shoot as a last resort.

The warehouse was filled with empty shelves and various clutter, but that couldn't disguise the fact that there was no alien to be seen. Gun still at the ready, Beckett headed further into the room, hoping to catch some sign of movement. But there was nothing. She deflated in disappointment. No one was in there but them.

"Beckett." The detective looked up to see Esposito motioning her over. When she came closer she saw a trapdoor near the corner, which looked like it led to a basement, probably once for storage. Hope restored, Beckett motioned for the Doctor to unlock it. The Time Lord obliged, and they quietly swung the trapdoor open to reveal a short ladder leading to a room below. The trapdoor fell against the ground with a clatter, and Beckett knew that wouldn't go unheard. If they wanted to keep the element of surprise, they had to act now.

Beckett jumped quickly down into the room, landed on her feet, and straightened immediately with her gun held up. "NYPD! Don't move!" Esposito and Ryan were quick to join her, but she didn't notice them. All she saw was the huddled shape on the floor. Cautiously, she and the other detectives approached, in case it was hiding a gun, but the creature looked to be in no shape to fight. It was the brown-skinned, cow-eared Fatorin they'd been chasing, but it seemed to be asleep, and wounded. Blood stained the strange leather suit it wore, seeping through and creating a puddle around it. Its face was bruised and scratched, and it appeared to be whimpering in its sleep.

Castle's voice sounded behind her. "What happened to it?" She turned to see that he and the Doctor were now behind the four gun-wielders, Castle looking confused, the Doctor looking concerned.

At the sound of Castle's voice, the creature jerked awake, wincing in pain at the sudden movement. It looked around with wide yellow eyes that held both fear and hatred. "Who are you?" the creature hissed. Its voice was British and male, with a deep, guttural sound to it.

In a calm tone, Beckett replied, "We're the police. What is your name?"

The alien glared distrustingly at her before lowering his head a little. "Crah," he finally answered. "Crah Rotir Sta."

Beckett nodded. "Alright Crah. We're here about the murder of the Arondrian Tikrah. Would you know anything about that?"

Crah blinked a few times before letting out a throaty, painful laugh. "Of course I do, I killed him after all." He spat out blood, eyes screwed tight with pain.

The detective blinked in surprise. That had been an easy confession – something was off. "Why are you admitting to it? Is murder not illegal where you're from?" She asked drily.

The alien laughed again, a hand clutching his ribs painfully. "Because it was necessary. There is nothing you can do to stop us now." Crah's eyes took on a feverish look, and he began speaking more rapidly. "When the Arondrians ran, we followed. We came with ships and guns and battle, and we will stay until this world is ours. All of it ours – for Raktor." He spat out more blood and began chuckling, an eerie, hollow sound. "I was seperated. Hunted the Arondrian, silenced him. He could not warn this world. Must not tell them what he had seen. What we had done. He fought back. Was strong. Used blade against me." The creature flashed a toothy, vicious smile. "I won."

The alien's feverish rambling sent a tremble through Beckett. The detective's breath caught in her throat. "How many of you are there?" she asked hoarsely.

"Many. So many." Crah seemed delirious now, a breathless chuckle forcing its way through his pain-clenched teeth. "So many tyron weapons. We will wipe you out of the sky. For Rakto-" The alien broke off for a moment, eyes bugging wildly. Then he let out an ear-piercing shriek, every limb going stiff, his back arching in agony. The humans hurried to help, but beyond pinning down his limbs so he wouldn't thrash and hurt himself, there wasn't much they could do.

The Fatorin gave a few spasms, then slumped against the ground, his crazed, feverish eyes becoming blank. Beckett blinked in shock, unable to comprehend what had just happened. Only a few seconds had passed, but Crah was dead.

Their killer was dead, but there was an entire invasion force to be reckoned with, and they had no idea how to prepare for it.

SCENEBREAK

They had gathered back in the top floor of the warehouse. It was too uncomfortable speaking near Crah's body, which they'd agreed to bury before they left. River could tell this didn't sit well with the detectives, but there wasn't any logical way of reporting this death, so they had no choice.

The four humans seemed very shaken by what had just happened. They sat close together, eyes shadowed, clearly trying to come to terms with the combined threat of invasion and watching Crah die so horribly in front of them. River herself was having trouble pushing images of the dying Fatorin out of her mind, but beyond that all she felt was anticipation. Finally, the waiting and sitting was over. The world was in danger again, and the mad chase to save it would be picked up. Another invasion to stop, another threat to face, all in a day's work.

Beside her, she could see the Doctor was similarly determined, though perhaps not as excited as his wife. He never responded well to death, even the death of a psychotic murdering Fatorin. Still, there was a certain air of anticipation about him as well. Now, finally, they were in their element. Saving the world was what they did.

"We need to find the rest of the Fatorins." That had been Beckett. The detective looked slightly pale, but determined.

"Oh, that's easy," the Doctor said absentmindedly.

Beckett jerked her head around to look at the Doctor. "Easy? What do you mean?"

The Doctor held up his sonic screwdriver in response. "This thing's been reading tyron energy like mad ever since we got in here," he explained. "I've got enough of a sample that I can trace it back to it's source, easy."

Esposito frowned thoughtfully. "So we just follow that energy thing and find the aliens, just like that?"

The Time Lord nodded. "Yeah, why?"

No one spoke for a few moments. Then, to River's surprise, Castle spoke up. "No. There's no way. It's been way too easy."

River's brow furrowed. "What do you mean?"

The writer stood, too full of nervous energy to stay seated. "All of this. Finding the tyron energy in the garage – I mean, it's not like the sword was shedding it everywhere they went, otherwise we would have found a trail, so what was so much of it doing at the garage? And why is there enough here to lead you back to the source? There's no reason for it."

Beckett seemed to pick up on her partner's train of thought, snapping out of her momentary funk. "And Crah. He was really badly wounded, which suggests he was in a fight."

"But Tikrah only had the one wound on his throat, which means he was taken by surprise and killed quickly," Castle explained.

"Tikrah wasn't a strong man even wearing a human shimmer, he couldn't have wounded Crah that badly."

Esposito and Ryan had listened thoughtfully, and now both were nodding. "There was something up with Crah too," Esposito pointed out. "He almost looked drugged or something."

"And he was way too eager to tell us about their invasion," Ryan added. "If he killed Tikrah to keep him from warning people, why tell us at all?"

River looked at the four humans in surprise. She and the Doctor had been so caught up in the idea of saving the world again and throwing themselves into the adventure head-first had kept them from really looking at the facts. The Doctor had rather an act first, ask questions later policy, but here these humans were, stepping back and actually thinking and planning things through. She wondered a little enviously what it might be like to actually have a plan for once.

The Doctor too seemed interested in the humans' theories. "So why do you think they're making it easy for us?" He asked curiously.

"Because it's a trap." The words were out before River had fully finished the thought. When the others turned to look at her, she explained, "They've basically laid out a trail for you to follow. They've probably got some sort of trap waiting."

"Yeah, but a trap for who?" Esposito asked.

River turned to her husband. Solemnly she told him, "I think it's for you, my love."

The Doctor blinked in surprise. "Me?" Then he thought about it for a few moments, his expression hardening. "I'm the only one with the technology to track it," he realized grimly.

The archaeologist nodded. "You have to admit the situation is rather tailored to you. Innocents hurt, an invasion to stop, Earth to save. How could you have ever resisted?"

The Time Lord's eyes hardened for a moment. "Once – just once – I wish my enemies wouldn't get it in their heads to go after Earth first." River knew some of the horrible fights he must be remembering, and her heart ached for him, but right now they needed to focus on the case.

Esposito spoke up again. "So if we follow that energy trail we're walking into a trap?"

River nodded. "We can assume."

"Then let's not walk into it." Everyone turned to see Beckett standing beside Castle, arms crossed determinedly across her chest. "Whoever's setting this trap, they're setting it for the Doctor, not us. They might not know about us."

The Doctor frowned. "What are you suggesting?"

"You go in first to get their attention, then we stay hidden and be your back-up," Beckett explained. "If you get in trouble we can get you out, but it'll be easier if they don't know we're there."

The Time Lord looked thoughtful for a few moments, then narrowed his eyes slightly. "Alright. But River's in charge."

The woman in question let out a snort. "Fat chance," she told her husband. "I'm staying with you. The Doctor always travels with a companion, remember? Anyone who's ever fought you knows that. It'd be a bit suspicious if you went in there alone."

The Doctor turned to his wife with an unusually serious expression. River faltered slightly at his unusually intense stare. "River, this is important," he chided gently. "You're the cleverest one besides me. If we need to dismantle some complicated alien technology, you'll be the only one besides me who'll know how to do it." In a quieter voice, he added, "And you're the only one I trust to keep the guns under control."

River felt a rush of warmth as the realized the depth of trust he was giving her. She had run with older Doctors before, true, ones that knew her even better, but this one loved and trusted her so much. It almost scared her to think what would happen when she lost that. She gave a grim nod. "Fine. But you still need a companion."

With a smile, the Doctor turned to Beckett. With an offered hand he asked, "Would you be willing to play the part?"

The detective blinked in surprise. Some strange emotion flashed in her eyes; River wondered if she was thinking about the night before and what she'd told her about traveling with the Doctor. Is she wondering what it would be like to actually be the Doctor's companion? she wondered thoughtfully.

After a few moments, Beckett accepted the outstretched hand. "Sure."

They had a plan. River just hoped it didn't turn out like the Doctor's usual plans.

If there's anything completely wrong or just plain gross about the second half, I apologize. It's nearly midnight and I probably should've stopped attempting to write a few hours ago, but I'm currently in a sort of haze being fueled by the need to finish this chapter. Or something. Either way, my writing's usually crap after a certain hour, so again I apologize. I especially feel like shooting the whole bit with Crah - it's way too abrupt, too cliche, too blah, but whatever, my brain's not about to come up with anything better.

We're closing in on the end here. Only a few chapters left - two or three if I'm guessing right. I really hope you've liked this story so far and you'll like the way I finish it. I tried hard to come up with a good mystery and an equally good explanation, and I hope I succeeded. Keep an eye out for the next chapter, I might even get it done tomorrow. If school's out because of snow, which seems to be the idea, then definitely.

The title is a reference to the Nikki Heat series, which is an actual book series written by a ghost writer pretending to be Richard Castle. In the books they refer to a fact that stands out or doesn't add up as an odd sock - and there's quite a few of them here.