Alexis Castle opens the door of her father's loft, walks in, looks around, and lets out a piercing shriek.
"Dad! Oh my gosh, are you okay? What happened? Dad!"
Her stepmother comes rushing in from the other room. "Alexis? What's up?"
"Kate! Where's dad, is he okay?" Alexis demands in a panic, grabbing the other woman's arm.
"What, uh, your dad's fine - he's right upstairs," Kate replies, confused. "Why?"
"Oh." Alexis releases Kate's arm and takes a deep breath. "Um, maybe I overreacted a little bit?"
Kate frowns at her in concern. "I think I missed something."
"I just-" Alexis gestures around at the living room, which looks the same as always - which is exactly the problem. "It's the day before Halloween and you guys don't have any decorations up."
"Oh," Kate says, a smile starting to spread over her face. "So of course you assumed that something terrible must have happened to your dad." They both nod at each other. "That makes perfect sense, but really he's fine, honey. It's just, Kevin and Jenny are bringing Sarah Grace and the new baby over tonight, and your dad was worried that the kids would be scared if he goes all-out with the decorations like he usually does. So he decided to tone it down."
"That sounds just like him," Alexis mumbles, blushing. "I totally freaked out for nothing. I'm such an idiot."
"No, no," Kate soothes, patting her shoulder. "It was a natural assumption, knowing your dad."
The man in question appears at the top of the stairs. "I thought I heard yelling. Everything okay down here?"
"Your daughter was just a little alarmed by the apparent lack of preparation," his wife tells him with a smile as he descends. "You have to admit it doesn't look very Halloweeny around here."
"Oh! But Lucy and I have it all planned out," he exclaims excitedly, coming forward to give Alexis a quick hug. "Lucy, show Alexis the Halloween setup."
"You got it, boss," says the computer voice, and suddenly the lights dim to dark red throughout the loft. Eerie sounds echo from the corners: shrieks, cackles, howls. A holographic projector hidden in the ceiling sends wavering images of skeletons and ghosts floating across the walls.
"We still need to work on those skeletons," Castle comments, frowning. "Lucy, the ones in the corner are off-center. They look like they've been decapitated, not that there's anything wrong with that, but the symmetry is off."
"Dammit, Rick, I'm a doctor, not an interior decorator," the computer replies, and the room returns to normal lighting, the spooky noises fading out. Castle's eyes go wide, staring at his wife.
"What - Did you teach her to say that?"
Beckett merely grins and walks away.
"Anyway, sorry to worry you, daughter," he says, putting his arm around Alexis. "Everything is completely under control, as you can see. I've got all the frightening decorations ready to go up after the little ones have come and gone. It's all set up." He frowns slightly. "Except I can't get Kate to tell me what costume she's planning. She's up to something."
"Well, whatever it is, you'll find out tomorrow," the redhead replies. "And that lighting stuff looks really good. You and Lucy did a great job with it."
"Thank you, Alexis," says the computer voice.
"Yes, thank you, and what are you dressing up as?" her father inquires. "You are coming tomorrow night, right? You know it's compulsory."
"Of course I'll be here, dad. I'm going as Julia Child, and Steve's going to be the Swedish Chef, so we're like a matched set." She grins, ignoring the way her father's face twitches at the mention of her latest boyfriend.
"Sounds good, pumpkin. Now, are you going to help me with Kate or not?"
"What? You mean to find out what her costume is?" Alexis shakes her head at her dad. "If she wants to surprise you, you should let her."
"You're probably right." He droops a little pathetically. "I just..."
"Dad." Alexis pats him gently on the shoulder. "You know what, I get it. Last Halloween you two were separated, so you're on edge. It's understandable."
"I just want everything to be perfect," he mumbles.
"I'm sure it will be. Whatever secret she's planning, it must be something she thinks you're gonna like, right?"
"Yeah, I'm just ... not as fond of surprises as I used to be, I guess."
"So this wouldn't be the time to tell you I'm dropping out of college to run away and join the circus?" Alexis teases. He frowns.
"Just for that, you have to help me remove the pumpkin guts in preparation for carving."
"You're tough, but fair, dad."
Kate approaches Alexis a little while later, after Castle has gone to wash the pumpkin mush off his hands ... and arms ... and chest ... and face.
"Hey, got a minute?" Beckett asks a little uncertainly.
"Sure. What's up?"
"I heard your dad trying to get you to help him figure out my costume," Kate says, and the women share a brief eye-roll.
"He's just curious, you know how he is," Alexis says apologetically. "He'll be fine."
"I know ... I really hurt him last year," Kate sighs, looking down. "I thought we'd gotten past it, but somehow Halloween has brought it all back up again. I really want to make it up to him."
"Well, it does sound like you've got something up your sleeve..." Alexis prompts, curiosity getting the better of her.
"I do, and I could use your help." Kate smiles tentatively at her stepdaughter. "If you don't mind?"
"Of course not," Alexis says, and when she hears what Kate has in mind, she gasps with excitement. "Oh my gosh, yes! I'll go get it right now." She grabs her purse and runs out.
Halloween evening arrives, and the loft is properly - albeit hastily - decorated. The place is hopping with Castle and Beckett's friends and coworkers in their various costumes. But Castle, in his Star Trek captain's uniform complete with real (fake) phaser at his hip, is anxious and twitchy, because his wife is nowhere to be seen.
"She should be out here by now. Are you sure nothing's wrong?" he asks for the dozenth time.
"Darling, stop fussing," his mother chides. "Alexis checked on Katherine and said all is well. She's probably just waiting for the right moment to make her entrance."
He looks across the room at his daughter in her Julia Child floral blouse. She gives him an encouraging smile and lifts her glass of punch in his direction.
"Dude, where's your wife?" asks Esposito, slapping Castle on the shoulder.
"Be here any minute," he replies distractedly, and then, focusing on the sergeant, "Nice costume, by the way, but with the amount of extra garlic you like on your pizza, you'd make a terrible vampire."
"Bite me," Esposito snarks.
"No thanks, I..." The sarcastic response dies on Castle's lips. His gaze is riveted on the slender form of his wife, who has finally appeared in the doorway from their bedroom.
"Kate!" he exclaims, making his way quickly through the crowd to get to her. He takes her hand and looks her up and down. She seems to be wearing her usual clothing, nothing out of the ordinary here: just the Captain of the 12th Precinct, dressed for work. "Please don't tell me you got an urgent call and you have to go in."
"Nope," she replies, smiling, nibbling lightly at her bottom lip. "Tonight I'm all yours, babe."
Castle examines her body again. "Well, then please don't tell me there's a frog on a spring under that blazer."
Kate laughs. "Castle, you never repeat a costume, and neither do I."
"Okay, then ... I don't get it," he pouts, looking into her eyes, which are sparkling with excitement and maybe a hint of nervousness. "What's your costume? You look just like you."
"That's because I am me," she says softly. "My costume is me, but ... different. Tonight, I'm me with a baby inside." She holds up a small white plastic stick.
Castle just gapes at her, at first uncomprehending, then speechless. She smiles a little, her eyes shining.
"Are you ... are you saying what I think you're saying?" he finally manages to gasp, placing his hand gently on her stomach. She bites her lip again and nods, covering his hand with her own. Then, looking across the room, she makes eye contact with Alexis, who nods back.
"Look," Kate urges, gently pushing on her husband's shoulder to get him to turn around. When he looks behind him at his daughter, he sees her pulling open her floral blouse to reveal a t-shirt underneath. Emblazoned across her chest are the words "I'm the Big Sister."
"Kate," he breathes, turning back to stare at his wife, whose smile now spills over and lights up her whole face. "Oh my god, Kate! Best Halloween present ever." He sweeps her up in a bear hug, laughing joyously. She wraps her arms around his shoulders and laughs with him.
"Sorry to make you wait for the surprise," she says, a little breathlessly, when he finally puts her down and pulls back to look adoringly into her eyes.
"No, no. No apologies necessary," Castle denies happily. "It was worth the wait." Suddenly his eyes go wide again. "But, oh no, we better get to work! We don't have much time!"
"Time for what?" Kate wonders as he pulls her to the couch and sits her down.
"To plan our Halloween costumes for next year!"