Beckett pulled into a street crowded with blue police uniforms, the gumball on her car's roof giving her automatic right-of-way over anything beyond the police barricades. She could tell the location of the crime scene by the coroner's van parked out the front, and contemplated where to park...park beside it and save her legs the walk, or park right here and spend the extra few minutes walking alone with Castle.

"What do you think Castle? Feel like walking with me or are you in a hurry to see a dead body?"

"The dead body sounds good." He sounded distracted, so she turned to look at him, surprised and slightly annoyed at his response.

He was face down into his cell phone, tapping away frantically as his phone beeped in response. She normally didn't mind him geeking out, and took particular delight in luring him out of it if it happened when they were alone - anything involving sheer silk generally worked, and there was that one time with ice cubes... - but this was the last few minutes they had before they had to put on their single-and-professional faces, and she'd rather he spent it with her than some new app.

She hit the brakes, hard, and he jerked forward, the phone flying from his fingers and bouncing off the dash and onto the floor. She glared at him as he looked around at her sheepishly. His cell beeped loudly, frantically, and they both looked down at it...the sound dwindled away, and they looked back at each other.

"And now my Angry Birds will never be free," he said, regretfully.

At least they were the only birds he was looking at online these days, she thought.

...

"I'm sorry, that's how I cope!"

She looked at him as they walked from the parked car to the crime scene. "You have to play Angry Birds? Being with me that difficult Castle?"

He looked at her, exasperated. "No! But I've never had to conceal a relationship before. I live on page 6 of the New York Times, this..." he waved his hands between them, "...is new to me."

"Trust me, it's kinda new to me too," she said.

He reached out his hand to stop her, just short of the crime scene.

"30 minutes ago, we were on my sofa enjoying the day...together. Now, we're entering a crime scene where I have to be careful about what I say, how I look at you and not able to touch you. It isn't easy."

She smiled at him. She'd always kept a solid wall up between herself and all but her closest friends...Castle's wall was made of tissue paper.

"That's the way it's been for the last four years isn't it?"

"Yes, but that's before we started sleeping together!"

"Toughen up Castle," she said, grinning. "Let's get this case out of the way and we can go home and play some games that'll give those Birds a reason to be Jealous, as well as Angry."

She turned and walked up the stairs. A heartbeat later, Castle followed, like an excited schoolboy.

...

The crime scene was the living room of a well furnished apartment. The body lie in the centre of the room, neatly posed on an expensive-looking rug and wearing an airline uniform, with an expensive hand-bag clutched under her left arm. The apartment was neat, and filled with the heavy scent of the exotic orchards sitting in expensive pots around the room.

"The victim is Alana Manning, 39, flight attendant, lives here alone." Detective Javier Esposito gave his brief summary of the victim and the crime scene. He knelt down and indicated heavy bruising on either side of her neck. "Judging by these marks, it appears Ms Manning was choked to death."

"She wasn't choked", said both Castle and Beckett together.

Esposito looked at the two of them, then at Doctor Lanie Parish, the Medical Examiner, who stood quietly watching with some amusement.

"Choking refers to death by cutting off the air supply, typically by direct force to the windpipe," Castle said. "The bruises would be on the front of the neck in that case."

"Those bruises indicate cutting off the blood supply, which technically falls under the definition of strangulation," Beckett continued. "Bruising is too wide to be a rope or belt, killer probably did it by hand."

Castle knelt down and examined the victim. "A rope or belt would also leave bruises around the front.

I'm guessing he strangled her from behind...there don't appear to be any frontal bruises consistent with the killer's thumbs."

Doctor Parish gave a little golf clap. "Good work Castle, you'll be wanting my job next."

Castle smiled at her. "What? And deprive these poor souls the undoubted pleasure of your delightful company Doctor?"

Lanie smiled back at the flirtation. She knew Beckett and Castle were together, but had always acknowledged Castle's inherent charms.

"Always the charmer Castle." She turned to Beckett. "Based on lividity and body temp, I put the time of death at about 8 hours ago, so around 10pm last night, give or take a few hours. Unless there's anything else you need, I'll be getting the body back to the morgue and see if I can give you a better window."

Beckett nodded. "Thanks Lanie. Let me know what you find."

"Will do."

As Doctor Parish moved past Beckett she threw a sideways glance at Castle. "And if you two blow it, I'm calling 'shotgun' on writer boy here," she whispered.

...

Beckett looked through the victim's hand-bag, finding nothing of substance...a bundle of keys, a small sudoku puzzle book and the usual paraphernalia. She saw movement out of the corner of her eye and looked up as the last member of her team approached.

"What have you got for me Ryan?"

Detective Kevin Ryan flicked through his notebook, highlighting key points of his findings. "According to the neighbors, Ms Manning was rarely home, kept mostly to herself when she was home, and no-one had a bad thing to say about her. Neighbors recall seeing a male visitor from time to time, but don't know any details."

Beckett nodded as she updated her murder board. "Probably a boyfriend. Pull her phone records, see if you can track him down."

"Way ahead of you. James Marsters, engineer. Uniforms are bringing him in now. Has a solid alibi for the evening though...was pulling the night shift at the factory he works at, witnesses confirm he was there from around 7 pm last night until 3 am this morning.

"Good work Ryan. We'll make this a chat rather than an interrogation then."

Castle closed the door after he and Beckett entered the small interview room, where Masters was sitting, distraught. He looked up as the door closed. Beckett held out her hand and Marsters rose to shake it.

"Mr Marsters, I'm Detective Kate Beckett, and this is Richard Castle, a consultant with the department. I'm sorry for your loss."

Masters slumped back into his seat as Beckett sat opposite him. Castle stood quietly by the door...this was an interview with a bereaved partner, not an interrogation with a suspect, and while Castle certainly had people skills, they were better off in social occasions with martinis. This required one-on-one empathy he just didn't have, and was definitely Beckett's baby.

"When was the last time you saw Alana, Mr. Marsters?" She asked.

He sighed, gathering his strength and clearly trying to focus. "Four days ago, just before she went on an international flight to Tokyo."

Castle looked at Beckett, then back to Marsters. "You hadn't seen her since she got back? She'd been back over a day."

Marsters looked up at him. "We never saw each other the day she got back. She was usually tired, and I'm always working nights. We were due to meet today, for lunch."

Beckett leaned forward. "Do you know if she was having trouble with anyone at work, or if there was someone in her building she wasn't getting along with?"

Marsters shook his head. "No, Alana got along well with everybody. She made friends easily and had a way with people. We've been together 3 years now and I can't even remember the last time we had an argument."

Beckett stood. "Thanks for coming in Mr. Marsters. If there's anything you can think of that might be of help, please give me a call. I'll get someone to drop you at home."

Marsters nodded and stood, checking his watch.

"If it's not too much trouble, I'm due at work soon. Can I get dropped off at the plant?"

"Plant!"

They both looked up at Castle, who stepped forward.

"Alana's apartment was full of plants. Healthy, exotic plants. Plants that need regular watering. Who watered the plants while she was away?"

"I did," Marsters said. "I have keys to her apartment, and she has keys to mine." He reached into his pocket and pulled out a set of keys and flicked through them.

"These are for my apartment, these are for hers, this is for my car. We have matching key chains...every key she has, I have, and vice versa. We started that after she left her keys in Shanghai two years ago, makes it easier to replace them if one of us loses our keys."

Beckett looked at the keys, puzzled by something. It took her a moment and then it dawned on her.

"Your keys are identical you say?"

Marsters nodded.

Beckett stood and left the room hurriedly, only to return a moment later with Alana's hand-bag. She rummaged around inside and pulled out Alana's keys, placing them side-by-side with Marsters' set. They were identical, except for a silver key with an orange tag.

Beckett picked up the silver key. "What's this one for?"

Marsters looked clearly puzzled. "I have no idea...it wasn't there last week."

Beckett examined the orange tag closely. "It's numbered. Could be a locker key. Gym locker maybe?"

Marsters shook his head. "She didn't like gyms, couldn't see the point in paying for them when she was overseas all the time. Said she got all her exercise running after passengers all day."

Castle looked over Beckett's shoulder at the tag. "C261 - that's a big number. Would have to be a big bank of lockers, too big for most gyms. Airport or Bus terminals?"

Beckett nodded. "I'll get the unies looking into it. Can't be too many terminals with lots of lockers, using orange key tags."