I'm fascinated by musicians who don't completely understand their territory; that's when you do your best work.
- Brian Eno

Beckett was charmed by Castle's daughter, who seemed to be astonishingly sensible and level-headed considering her origins. On the short ride in the town car to the restaurant, Alexis chattered away about her school day and her debate team meeting. Kate was impressed by how tuned-in Castle was; from the questions and comments he put in, it was clear that he knew all of his daughter's friends and teachers, and the subjects she was studying, including her debate topics.

Soon enough they were at Antonio's - where Martha Rodgers, the well-known stage actress, was greeted like a queen - and settled in at a private table in the corner, looking at menus while Martha perused the wine list. "What do you like, Katherine, dear?" she asked. "Red or white?"

"Red, please," Kate replied, although she didn't plan to drink much. She observed with some interest how the waitstaff fawned over Martha, and how Castle winced and fidgeted in his seat when his mother flirted back flamboyantly.

"How were the rehearsals today, Ms. Beckett?" Alexis asked Kate politely, after ordering had been taken care of.

"Oh - fine," Kate replied. "And please, call me Kate. Do you know Messiah well, Alexis?"

"No, but Dad has been playing it nonstop at home," the girl said. "Or, he was, until he started this new opera."

"Oh yeah, he mentioned that," said Kate, looking over at Castle, who looked oddly nervous, his eyes guarded. "So he's been working on it a lot, huh?"

"Up till all hours the last few nights," Alexis nodded. "But he still won't tell me what it's about. What's up with that, Dad?"

"Just not ready to talk about it yet," he mumbled, avoiding their eyes. "Mother, how did your show go last night?"

Martha launched into a lengthy story about a wardrobe malfunction and backstage drama involving several of her costars and a costume designer, which got them all laughing. But Kate hadn't missed how quickly Castle had changed the subject when his new opera came up.

The conversation flowed naturally, and, as they were all finishing off their appetizers, Alexis got up the nerve to turn to Kate and say tentatively, "I was really sorry to hear about what happened with your mom."

"Oh - thank you," Kate said, a little awkwardly, wondering how much Alexis knew and what was appropriate to share with a teenager, albeit a particularly mature one. She saw Castle holding his breath, watching her anxiously, clearly hoping that his daughter wasn't upsetting her. She gave him a small reassuring smile and saw him relax slightly.

"It must have been really hard for you," Alexis added quietly. "I hardly ever see my mom, but at least I know she's there."

"Yeah," Kate said, taking a fortifying sip of her wine. "It was hard. But I had my dad, like you have yours."

"Yeah," Alexis agreed, flashing a brilliant smile at her father. He smiled back and Kate felt an unaccountable flutter in her chest. Seeing Castle interact with his daughter was ... unsettling. It was a whole new side of him.

"So, Katherine," Martha interjected, "tell us more about yourself, dear. Are you seeing anyone?"

"Mother," Castle groaned, and Kate couldn't help smirking, enjoying his discomfiture.

"What, darling? I'm just making polite conversation," Martha declared, but her eyes sparkled with merriment.

Kate considered deflecting the question, but she knew Castle would pick up on that, so she said merely "No, my life is pretty busy and I don't have much time for dating."

"I see," said Martha shrewdly, and Kate couldn't even bring herself to look at Castle.

So instead she turned to Alexis and asked, "What about you, Alexis? Any cute boys in your life?"

Alexis turned pink and giggly, and Kate was able to glance over at Castle now, biting her lip with amusement at the look of outrage he was directing at her. He clearly didn't want to think about his daughter dating.

Kate smirked at him and pretended not to notice the way Martha was looking at them both.

Fortunately, talk of Alexis's male acquaintances led Martha into another series of anecdotes, and the conversation moved on.

As the town car pulled up outside Kate's building, she said, "Thank you all for having me along to dinner. It was nice meeting you, Alexis, Martha."

"The pleasure was ours, darling," Martha replied. "I hope you'll join us again soon."

"Dad will walk you to the door," Alexis added, giving Castle a significant look, and he startled and reached for his seatbelt buckle.

"Oh, uh, yes, of course," he stammered. Kate suppressed a grin, unbuckling her seatbelt as well, and was surprised when Alexis leaned over to give her a quick hug.

"It was great to meet you," the girl said, and Kate smiled at her.

"You too. See you at the concert."

Castle held the car door for her as she gathered up her bag and violin case, and then he walked beside her to the front door.

"That's a great kid you've got," she said as they came to the entrance of her building.

"Yeah," he agreed, his face lighting up. "Somehow she's turned out well, despite all my efforts."

"Oh, don't sell yourself short, Castle. You must have had something to do with it." She grinned and added, "You contributed some genes, at least. Maybe the good sense and competence skip a generation." She paused, glancing back at the car, and amended, "Or two."

Castle snorted a short laugh, acknowledging the jab. "Thanks for coming to dinner, Beckett. It was nice."

She frowned a little, pondering the implications of that, but before she could respond, he added, "And I really am sorry about-"

"Castle," she forestalled him, lifting a hand. "It's fine. Don't worry about it."

He tilted his head to one side, scrutinizing her expression. "You're sure?"

"Yeah."

"Beckett," he sighed, rubbing his forehead. "The murder case - and the solos - the dress rehearsal tomorrow."

"Is there a question in there somewhere?" she laughed softly, her smile widening when he huffed. "Castle, your family is waiting. You should go. We'll figure everything out tomorrow."

"Everything?" He perked up. "Even the murder?"

"Ugh!" she groaned. "Listen ... just come to Symphony Hall in the morning, and we'll call Detective Gates. We have to make sure she has all of the information we've collected, and she - What?" she demanded, seeing Castle's gleeful grin.

"You said 'we,'" he pointed out, his eyes twinkling. Kate groaned again.

"Don't get any big ideas," she said, but then she thought about his mother and daughter in the car, waiting, and probably watching them - Kate resisted the urge to glance over and confirm - and the corners of her mouth twitched upward mischievously.

"Thanks for a lovely evening, Castle," she said, and lifted herself up to brush her lips across his cheek.

Then she turned on her heel and opened the door, stepped inside her building, and let the door close behind her, not looking back.

Castle stood still on the front step of Beckett's building, stunned into immobility for a long moment. At last he snapped out of it, blinking, and hurried to walk back over to the waiting car.

As he caught sight of his mother's and daughter's faces, he groaned to himself, and it occurred to him that Beckett had set him up. That devious, infuriating woman! She had known exactly what he was in for when he got back into the car.

Yet, with the phantom impression of Beckett's lips still tingling on his cheek, he couldn't quite bring himself to care about the grilling he was about to experience.

In any case, it was just another on the long list of distractions taking up space in his head right now. It had been a busy day; between the numerous revelations they'd had about Annabel's murder, the searing shock of Beckett's disclosures about her mother, the rehearsals themselves, and the dinner, he had so much to think about it was making him dizzy. His mind raced the whole way home, as he sat in the car trying not to respond to his mother's just-shy-of-indecent innuendos and his daughter's excited questioning.

"I really liked her, Dad," Alexis said, gazing soulfully at him, her blue eyes wide and sincere. "She seems so smart, and nice, and interesting, and she doesn't take your crap."

"All true," he had to agree. "But there's nothing going on between me and Beckett, honey. We're just working together, and trying to solve this mystery, and-" He stopped cold, realizing what he had said, just as the two red heads whipped around to stare at him. Oops.

"What did you say? Solve what mystery?" Alexis demanded.

"Uh, wow, that linguine was excellent, wasn't it?" he tried, and winced when his daughter folded her arms across her chest and fixed him with a stern glare.

"Dad."

"Okay, listen, it's not a big deal. It just so happens Beckett is the person the performers always come to with their questions and stuff, so a lot of them have been giving us information about Annabel."

"The singer who got killed?" Alexis asked, her eyes wide. He sighed.

"Yeah ... So we've been getting all these clues and sort of, uh, investigating them."

"Investigating? Dad, you're not a cop. You're not even a mystery writer."

"I know, I know," he said, "and Beckett has reminded me of that fact at least a dozen times so far this week." He pouted, hoping Alexis would soften, but no such luck. "But as I keep telling her," he went on quickly, "there's no harm in it. We aren't interfering; we're just gathering facts, and passing along everything we find out to the police."

"Still," Martha said, frowning, "it sounds dangerous, and you're just supposed to be conducting, darling."

"I am!" he protested. "Really, the rehearsals have been pretty easy, because everyone knows the music so well. The concerts are going to be great. Even more so if Beckett will agree to sing the soprano solos."

"Sing?" Alexis asked. "I thought she was a violinist."

"She is, but she used to be a singer, before her mom died."

Much to his relief, the car pulled up to the curb alongside their building just then; Castle did not at all want to get into any more discussion about Beckett with his mother and daughter. As they got out of the car he could feel his mother's eyes on him, but he pretended not to notice, and whatever she might be thinking, she kept her own counsel.

Upstairs in the loft, he stood next to his piano, lost in thought. The tragedy of Johanna Beckett floated through his mind, and he saw webs of connection forming between her story and the one he was weaving in his new opera.

He would never dream of putting real-life details into his operas, but he could already see how the emotional core of Johanna's and Kate's story would suffuse the new narrative he was creating.

"Dad?" Alexis asked softly from the bottom of the stairs. "Are you going to be up all night composing again?"

"Hmm? Oh - probably," he replied distractedly, although he hadn't sat down yet. He went to the window and stared down at the glittering lights of the city, thinking.

Vaguely he was aware of his daughter calling goodnight, and his mouth making some kind of appropriate response, but his thoughts were a full twist of the space-time continuum away.

Eventually he pulled himself away from the window, sat down at the piano, and began.

When Kate let herself into her apartment, the phone was ringing. She quickly put down her purse and violin and made a dash to grab it before it went to voicemail.

"Hello?"

"Hi, Katie, it's Dad."

"Oh! Hi, Dad," she said warmly, kicking off her shoes and shucking her coat. "How's your week going?"

"Fine, just fine," Jim Beckett said. "Not much exciting going on right now. The holiday season is slow for litigation, you know."

"Right," she murmured. "It's always quiet for you this time of year."

"Yep, and always busy for you, so I just thought I'd check in. It's Messiah week, right?"

"Yeah. You're going to come, aren't you?"

"You know I never miss it," he said, and she could hear the smile in his voice, and she did know it was true. Jim always came to at least one performance from each concert series.

"Listen, Dad..." she began carefully, sinking down onto the couch. "There's something you should know, before you come to the concert."

"Is it about that soloist who got killed? Terrible business," he said soberly. "Did you know her well?"

"No, not really. But ... the thing is, they haven't been able to find a replacement to sing the soprano parts."

"Oh?" he said, and she could tell from his tone that he had no idea where this was going.

"Yeah, and, um ... the conductor ... suggested that I should sing them."

There was a long, heavy pause. When Jim spoke again, his voice was thick with restrained emotion, and Kate had to close her eyes and swallow hard. "Are you going to do it?" he asked.

"Um, I haven't really decided," she lied, her voice small, her throat tight. She heard her dad sigh unevenly.

"You don't have to lie to me, Katie. That isn't your 'I haven't decided' tone."

"Dad..." she got out, and her throat closed up again.

"You should do it," he burst out, the words coming quickly, fervent. "I, I think you should." Another short pause. "I would love to hear you sing again, baby."

A tear rolled down her cheek, and another. "Really? You wouldn't be..."

"No." His tone was firm now. "No, Katie, don't worry about me. You should do it. If you want to, I mean, and I think you do."

She sighed out a long slow breath. "Okay. I'll, I'll think about it. You'll come to the concert, though? Saturday at one. I'll leave a ticket for you at will-call."

"I wouldn't miss it."

Kate swiped the back of her hand across her eyes. "I love you, dad."

"Love you too, Katie."

After hanging up, Kate went into the bathroom and started the tub filling. Her eyes were still wet, but she felt better for having talked to her father and received his ... blessing? absolution? approval? Whatever it was, she hadn't realized that she needed it, but somehow Jim always seemed to know when to call.

She settled back into the bubbles and let her mind drift. But it wasn't her father, her mother, the music, or Annabel that came into her thoughts as the hot water loosened her muscles and weighted down her eyelids. It was Castle: the feel of his stubbled cheek under her lips, the smell of his aftershave, the look of surprise in his deep blue eyes when she had leaned up toward him.

She closed her eyes and firmly forced her focus back onto the music.

Castle sat at his piano for an hour or more, the music flowing freely out of him and onto the page.

When he finally blinked his way out of it and looked around, he found his mother sitting on the sofa opposite, a glass of brandy in her hand, watching him.

"Mother," he said, his voice raspy from the long period of concentration. He got up from his piano stool and went to the side table next to the sofa. As he poured a drink of his own, Martha silently held up her glass for him to refill.

"You're going to have to tell her," she said, low-voiced.

Castle winced, coming around the arm of the couch to sit down beside his mother. He didn't bother pretending not to know what she meant.

"I can't," he admitted, speaking toward the liquor, avoiding Martha's eyes. "Not yet."

"Oh, 'not yet' is a coward's phrase, my boy," the redhead pronounced, leaning forward to put her hand on his knee. "The sooner the better, Richard. That gal deserves to know what you're up to, making her story into an opera."

"It's not her story," he mumbled, wincing again as he heard himself making weak excuses.

"It's her, though, darling," Martha said gravely. "Her character, her personality." She waited until he looked up at her. "Her ... soul. Isn't it?"

Castle sighed deeply. "I can't help it, Mother. She's ... extraordinary. I can't get her out of my head. Her, or this opera."

"I can see that," Martha murmured. "And that's why you need to tell her, Richard. The sooner the better."

On Friday morning Kate woke up early as usual and went for a run, with her earbuds playing peppy pop music and her mind carefully blank.

Energized by the exercise and the crisp cold weather, she returned home, showered, and ate breakfast. Then she pulled out her violin and spent an hour practicing before she set off for Symphony Hall.

The front lobby of the building was empty and silent, but the administrative area in back was buzzing with activity. It was the day before the first holiday performance of the year, and the New York Symphony's PR machine was revving up.

Kate checked in at Howard's office; he was on a conference call, and Lois had nothing new to report. "But he's going to want to know what you have planned for the soprano solos," Lois said, "so check back again soon, please, Kate."

"I will," Kate promised, although her stomach was still a little queasy at the thought.

Castle appeared at her elbow as she started down the hall toward the library. "Good morning," he said, offering her a coffee cup. She pursed her lips but took it without comment.

"Morning."

"I had some thoughts," he said, holding the library door open for her, and she rolled her eyes.

"Well, there's a surprise."

"Don't be mean," he chided. "Let's look at the diagram, okay?" He took out his notebook, already open to the page where he had sketched out the evidence and suspects in Annabel's murder.

"Down to just one suspect again," Beckett commented, looking at the page as she slid into a chair at the big table.

"Yeah," Castle agreed, sitting down next to her, "but here's the thing: if Sara the soprano isn't our killer, then who was the woman arguing with Annabel in the stairwell?"

"Oh." Kate paused, chewing her lower lip. "You're right, Castle. Something doesn't make sense here. From what Laura said, the argument in the stairwell took place just minutes before Annabel died." She sipped her coffee and thought about it. "So if the woman she was arguing with isn't the killer, then she had to have seen or heard something. But why hasn't she come forward?"

"If we could figure out who she was, we might be able to answer that," Castle said. "Now, mind you, I still haven't fully ruled out Howard. He could be a secret cross-dresser for all we know."

Beckett spluttered, nearly choking on her coffee. "That's your new theory, Castle? Howard in drag? Are you kidding me?"

He ducked his head, grinning sheepishly. "Well, it's a thought. We could also look at Chloe, the alto soloist. Annabel's death created an opportunity for her, after all."

"Yeah, but adding two solos to her Messiah performance isn't exactly a huge career boost. It's not even a lot of extra money." Beckett frowned, considering. "No, I can't really see it," she said after a moment. "But I suppose anything's possible."

"I know, it's a long shot," he conceded. "I just put Chloe over here in the corner with a question mark. Other than that, we're back at square one."

"We need to call Detective Gates," Kate said firmly. "I was thinking about it this morning on the way in. We've had so many people come to us with information, and I told them all to call Gates and tell her what they told us, but we don't know if any of them actually did. So we need to make sure she has all the evidence."

Castle opened his mouth to reply, but just then Beckett's cell phone rang. Raising her eyebrows, she signaled him to wait and pulled out her phone.

"Hello?"

"Ms. Beckett?" said a deep, mellow male voice. "This is Daniel Tate, from the symphony chorus."

"Oh - Daniel," she said, surprised. Beside her, she felt Castle straighten up attentively.

"I wanted to speak with you about Annabel Matthews," the lawyer said. Kate nodded eagerly, even though she knew he couldn't see her.

"Yes, of course. Listen, let me apologize for whatever Maestro Castle might have said to you yesterday," she began, ignoring Castle's affronted glare, but Daniel's soft chuckle cut her off.

"There's no need, Kate. I'll admit I was a bit put off by his approach - he came on a bit strong - but now that I understand you've been collaborating with the police, I can see where he was coming from."

"Collaborating is a little strong," she said cautiously. "We've just been sending some witnesses to Detective Gates, that's all."

Castle leaned closer, trying to get his ear near the phone, and Kate pushed him away, ignoring his scowl.

"Yes, she told me," Daniel said. "And I understand you were the ones who initially found out that Annabel and I had a meeting on Tuesday."

"Right," Kate said, giving in and switching to speakerphone mode so that Castle could hear. "So we were just hoping you could shed some light on why Annabel wanted to change her contract with the symphony. We know that Howard Grainger had been upset about it."

"I don't know anything about that," said Daniel slowly. "What Annabel wanted to talk to me about had nothing to do with her singing contract."

Beckett and Castle looked at each other in surprise. "Really?" Kate managed after a moment. "But…" She trailed off, realizing that they had jumped to a conclusion that had shaped their entire approach.

"Daniel, if you don't mind us asking," Castle cut in, "what was Annabel asking you about, then?"

When the lawyer answered, they both sucked in long breaths of surprise. So many things began to make sense in Kate's mind all of a sudden. Looking down at Castle's diagram, she finally saw where the lines of connection needed to be drawn.

"...And that's all I can tell you according to my confidentiality constraints," Daniel said. "Of course, I've already told the police all of this as well."

"Yes, of course," Kate murmured. "Thanks very much, Daniel."

They hung up, and she and Castle blinked at each other.

"I know who the killer is!" they exclaimed in unison.

They held eye contact for a long, charged moment. A smile began to curve the corners of Kate's mouth.

Quickly she reached into her bag, pulled out Detective Gates's business card, and punched in the numbers.

"Gates," came the voice through the speakerphone.

"Hello, Detective," Kate said. "This is Kate Beckett at the New York Symphony. We have some information for you."