Castle watched as Detective Cage pulled out the leather wallet with her badge, only this time the paper was completely blank. "I'm guessing this fell out of the TARDIS when you crash-landed. I found it on top of the empire state building." Her voice was a mixture of smug pride and amusement.

The Doctor leaned back with a childish pout. "I didn't crash," he insisted with a dignified sniff. "I made an improvised landing."

Cage raised an eyebrow. "You should be more careful with the TARDIS," she scolded, though her eyes shone with amusement. "She doesn't exactly appreciate these crash landings."

The Doctor's pout deepened. "I didn't crash."

The detective just rolled her eyes and asked, "Where are Amy and Rory?"

From behind the one-way mirror, Castle turned to Beckett. "Who?" His partner just shrugged, keeping her narrowed gaze focused on Detective Cage.

The Doctor's cheerful expression faltered. A look of deep sadness stole over his face for a moment, before being replaced by a forced smile. "Oh they're fine, they're safe." His smile faded, his eyes glazing over. "They're gone," he admitted dully.

Understanding flashed in the detective's eyes. "You just left them behind after the hotel," she realized aloud.

"Well, not just. It's been a while."

Cage chuckled. "Alright then. Shall we do diaries?" She reached into her bag and pulled out a tattered blue journal. She opened it carefully, skimming through the pages with respect for the book's age. "Let's see. Have we done Demon's Run yet Doctor nodded. "Yes. Have you done Lake Silencio?"

Cage's hands paused for a second, her smile faltering. "Which time?" she asked with a failed attempt at flippancy. Then she smiled again. "Yes, I watched Lake Silencio, about a week ago."

The Doctor's eyebrows rose in surprise. "Huh. It was around a week ago for me too. Looks like we're at the same place for once."

Cage's smirk softened into the first genuine smile Castle had seen her use. "Well there's a rarity." She leaned forward with a suddenly serious demeanor. "So what were you doing at that crime scene? You think whoever did that was alien?"

Castle's brow furrowed. "If you ask me," he remarked to Beckett, "she's doing a really good job at playing along." Beckett shushed him, her glare shifting between Cage and the Doctor.

The Doctor pulled out his sonic screwdriver and showed it to the detective, who frowned at what she saw. "There were traces of tyron energy near the body," he informed her. "So, alien I'm not sure about. And I can't be sure it was the killer. But someone who was at that garage is a time traveller."

Cage frowned thoughtfully. "Tyron energy's pretty serious. We need to find whoever's behind this." She rose, reaching across the table and pulling the Doctor to his feet. "C'mon, we've got an alien to catch." A playful smirk played on her lips. "Geronimo."

She led the suspect out of the interrogation room with the authority back in her posture. Beckett hurried over to intercept. "And where exactly are you taking my suspect?" she demanded.

Cage swept carelessly past the detective, tugging the Doctor along behind. "To my precinct. I'll be able to process him more thoroughly there, and there's a number of other cases he's been involved with that are being handled there." She threw the Doctor a smirk over her shoulder. "Besides, I like having him where I can see him." The suspect's ears went red, and he looked away quickly.

Beckett opened her mouth to argue, but Cage just sighed patiently and flashed her badge again. With a clenched jaw Beckett let them pass. Cage smirked. "Thank you dear. I'll let you know if we can help with the case at all." With that, she led the Doctor out into the elevator, giving a little mocking wave as the doors closed behind them.

For a moment, Castle and Beckett just stared after her in shock. Castle blinked a few times, not believing what he had just seen. That woman had just waltzed in, stolen their only suspect, a d waltzed out without so much as an explanation. A thousand thoughts crossed his head, but what he finally settled for was, "Did that strike you as a little odd?"

Beckett's eyes had taken on that steely look; Castle knew she'd thrown herself into full-blown detective mode. Cool, calculating, utterly determined. She turned away abruptly and strode over to the murder board. "It's out of our hands, Castle." Methodically she added the new information about Karrow to the board. "Cage is way above my pay grade."

"Yeah, and when has red tape ever stopped you?" Castle asked with a smirk.

Beckett let herself smile briefly. "After we talk to Karrow's family, I'll give Cage a call." Castle smiled back. He knew Beckett would never let a suspect go if they were needed to bring justice for a victim.

SceneBreak

A boy of sixteen with his father's curly hair was there to greet them when the detective knocked on the Karrows' door, but a teenage girl's voice rose up from in the house. "John, what did I tell you about answering the door?" A girl about Alexis's age shooed her brother away from the door, glaring at the strangers distrustingly. There was a fierce, wary look in her eyes, like a cornered animal. Castle frowned as he took in the teenage's tense posture and guarded look. All of his fatherly instincts protested against that hunted look. Something was definitely wrong with this picture.

The girl brushed her short brown hair out of her lightly freckled face, her strange gray eyes flicking from the detective to her partner. "What do you want?" There was a sharp edge to her voice.

Beckett held up her badge. "Detective Kate Beckett, NYPD. Are you Tanya Karrow?" The girl nodded warily. "Can we come in?"

Tanya narrowed her eyes. "Why?" she asked curtly.

Beckett raised an eyebrow at the girl's strange behavior but didn't comment. "It's about your father," she explained gently.

Tanya stiffened, her expression flashing from hope to fear to distrust with terrifying speed. "Is he okay?" she asked hoarsely.

Beckett sighed. "I'm afraid not," she told the girl gently. "He was found murdered this morning. I'm sorry."

Raw grief blazed in the girl's eyes, and she stepped back with a choked cry. For a moment she looked completely vulnerable. Then her shields went back up and those gray eyes turned to steel. "Right." Her voice had an authoritative edge now. "You can come in and ask whatever you want. Just leave my brothers alone, all right? I'll break it to them myself. I don't need some police morons screwing up the job." She opened the door fully and retreated into the house, leaving Castle and Beckett to follow.

Tanya led them to a homey-looking living room. From Tanya's behavior, Castle had been expecting run-down and ramshackle, but it actually looked quite comfortable. A little small, but Karrow hadn't been a rich man after all, and it was charming for its size. Two sofas sat angled opposite a fireplace with a TV above. Tanya sat on one, gesturing for the partners to sit on the other. Gone was the fear from before. Now she was full-on defiance and glares. "What do you need to know?"

Beckett switched from comforting mode to detective mode. "When did you last see your father?"

"Yesterday morning," Tanya shot off. She crossed her arms in front of her chest. "He didn't come home before I went to bed last night, which was around ten, so I just assumed he was working late. He does that sometimes. This morning I got the boys ready for school and assumed that Dad had gotten an early start. Also not unusual. He and Mindy run that store on their own, so they often have to work weird hours to get everything done."

"Do you know if there was anyone he was having problems with? Maybe someone at work?"

The answer to this question often became huge influence on a case. It could provide new leads, but it also revealed a lot about the person being asked the question. If they gave the answer too quickly, it was probably a bluff. Too eagerly and they had their own problems with the person. Not answering at all too quickly meant they were evading.

Tanya, however, gave a new response. Her steely look became one of raw hatred, her hands clenched so tightly on the sofa cushions that her knuckles went white. Then the moment passed, and she was emotionless. "No one at all," she answered flatly.

Beckett and Castle shared a swift look before turning back to the girl. "Are you sure?" the detective probed. Something about this was definitely off.

Tanya nodded, a strange glint in her eyes. As if she was hearing the punch line of a joke no one else knew. "Positive," she insisted. "Tim was a quiet guy. Mindy and us are about the extent of his social life. And I know he didn't have any problems with Mindy. It was probably just one of those random muggings, you know? Some street thugs who thought it was fun to take out a harmless librarian." That hatred blazed in her eyes again.

Before the detective can reply, two young boys of about six came running in. They tugged at the older girl's shirt like impatient puppies. "Tanya, Tanya! Can we watch the TV now?" Two identical, innocent faces looked pleadingly up at her as the ginger, curly-haired twins bounced around their sister.

Something in Tanya's face softened. "Not just now, you two." With ease she crouched down to their level, a hand on one boy's shoulder. For a moment she looked almost motherly. "Ron, take Erik upstairs and show him that spider you caught earlier. Alright? I'm just talking to the nice detective here. We'll be done soon." As she turned back to Castle and Beckett, her posture became rigid, as though trying to shield her brothers from the detective's view.

"Actually, I think we're done here." Beckett got to her feet, Castle following suit. "Do you four have somewhere to stay?"

Tanya stiffened, but after a moment she nodded. "Our Aunt Blanche'll take us in," she said firmly.

The detective raised an eyebrow. "We don't have any records of an aunt."

Tanya's gray eyes hardened. "Check again," she challenged. "Blanche Sheet, older sister of our mother Mary, age 50. You'll find her." She drew herself up to her full height. Somehow, with the two little boys behind her, the skinny teenage girl in a baggy sweatshirt managed to look intimidating. "Now if you could leave so I could talk to my brothers, I'd appreciate it. I'm sure you understand, detective." Her tone was biting on the last word.

SCENEBREAK

On the drive back, Castle was the first to speak. "Alright, is it just me, or was she hiding something?" Sometimes it helped to state the obvious, if only to annoy Beckett.

The detective shook her head grimly. "There's definitely something she's not telling us about her father being threatened. But we're not getting much more out of her right now. Let's just go where the evidence leads us, and if we have to talk to Tanya again, we'll have some facts to throw at her."

Castle gave his partner a worried glance. "Do you really think she had something to do with her father's murder?" Tanya had been uncooperative, yes, but she was clearly protective of her brothers, and she was only seventeen. Alexis's age, he thought sadly.

Beckett sighed. "I don't know castle. I hope not." Then she straightened her back and the detective took over again. "But either way she's hiding something, and we have to find out what."

SCENEBREAK

Back at the precinct, Beckett snapped more pictures on the murder board. "Tanya Karrow, seventeen, John Karrow, fifteen, and Ron and Erik Karrow, six." The four pictures were filed under the "Family" section of the board; "Suspects" remained blank except for the mugshot of the mysterious Doctor. The timeline was still pretty scarce, but it was a start.

Castle watched as his partner leaned against the desk, staring intently at the murder board. "Did you find those records on that Aunt Blanche?"

Beckett's brow furrowed irritably. "Yes, just like Tanya said," she said in annoyance. She turned to her partner. "Castle, I looked through Karrow's entire family, and there definitely wasn't a sister-in-law there before."

Castle shrugged. "Maybe something was wrong with the file," he suggested. Then he brightened, a grin spreading on his face. "Or..."

Beckett rolled her eyes. "Or what?" she asked resignedly.

"Or that time traveling Doctor used futuristic technology to change the records!"

His partner threw him a glare that couldn't entirely hide her amusement. "You're just not letting this time travel theory go, are you?"

"Oh come on!" Castle hedged, "Lightsaber cut marks, guy with a sonic screwdriver thingy, and records mysteriously changing! It all fits!"

Before Becket could retort, the phone on the desk let out an insistent ring. The detective picked it up. "Beckett." She listened for a few seconds, then nodded. "We'll be right there." She hung up, then grabbed her coat from the chair. "That was Lanie. She found something she needs us to see."

SCENEBREAK

"Thanks coming so quickly," Lanie said as she led the two into the lab.

"It sounded pretty urgent," Beckett replied. "What's up?"

Lanie swept right past Karrow's body, which was laid out on the dissection table with a cloth draped respectful over, and led them to a table where a microscope sat out. "Bear with me, alright, 'cause this is kinda freaky." There was unusual tension in Lanie's tone.

Beckett nodded, sharing a worried look with Castle. "What is it?"

Lanie leaned against the table with one hand and turned to face the detective. Slowly she explained, "So I took a few swabs of tissue off the burn marks around Karrow's throat to analyze. I thought maybe I could find a hint of whatever might have caused it."

"Alright," Beckett said warily.

"Well, I didn't find it, but what I did find was really weird. These tissue samples aren't human."

Whatever Beckett had been expecting, that clearly wasn't it. The detective looked well and truly stunned. She gaped at Lanie a few seconds before regaining her voice. "What?" she asked weakly. Castle had let out an audible squeak at Lanie's words, and now he was listening with mounting excitement.

"You heard me," Lanie replied.

"But you said you took them off Karrow."

The medical examiner nodded. "I did. Then I took another sample from elsewhere on the body, and another. They all came out the same; not human. It's not anything I recognize either. I don't know how it's possible, but I will say your vic here must have been into something pretty freaky. You can't just change your DNA like that."

Castle, whose excitement was now at the boiling point, turned to Beckett and whispered excitedly, "Not in this time period." And for once, his partner had no retort.

Again, I know nothing of science or DNA or any of that, so if I'm wrong, don't shoot me. But feel free to tell me. And I'm really starting to enjoy this fic. The mystery's more fun to write than I was expecting.