Title: Masks

Rating: It's a good thing I'm not a super conservative religious person or I'd be waiting for lightning to strike me for writing this.

Summary: There's a reason that Gates doesn't like to send Beckett and Castle on undercover assignments.

Disclaimer: I'm sorry, but did you realize what site you were on? Of course I don't own anything!

Dedication: This entire series is dedicated to the amazing writer kimmiesjoy. First off, she is just about as filthy minded is I am and her writing is brilliant, and secondly, because she is an amazing friend and such a wonderful fan who always knows how to make me smile. Honestly, if it were up to her my ego would be bigger than Castle's by now. Thanks for all the kind words and sexy stories, babe! This series is all for you!

Let it never be said that Castle did not know how to party. Although he was no longer one of the bright young things, he still knew how to have a good time. Still, he was beginning to develop a serious pet peeve about the music in this club. It was so loud he could barely hear himself think, let alone communicate with Beckett.

Beckett herself was people watching through half-lidded eyes, a lazy smirk dancing across her lips. Her dress was so tight that it clung to her body like saran wrap, its bright blue color playing off the flashing lights of the club. The 'vodka and tonic' that she'd been nursing for the past hour was cradled in her hands as she leaned back against the bar, propped up on her elbows.

"How much longer until our friend arrives?" Castle bellowed over the pounding music.

Beckett glanced around, looking like a cat on the hunt. Or a single girl trying to find a hot hookup. Either way, her expression matched that of the truly single young partiers drinking alone at the bar.

"Shouldn't be for another hour." She said. She didn't roll her eyes or sigh, but the way she bit her lip was decidedly not coy.

Castle shifted in his bar seat. "Any chance we could… you know… slip away?"

Beckett gave him a look, then glanced around the club again. She was bored. She'd done stakeouts and undercover work before – just never the two of them together. It was actually pretty mind numbing.

"C'mon, Castle." She said, grabbing his hand. "Let's dance."

She led him out onto the dance floor. Castle turned her, placing his hands loosely at her waist. She draped her arms on his shoulders and moved in time with the music, twisting her hips and pressing herself up against him.

"This isn't exactly protocol, is it?" Castle asked, pulling her a little closer.

"Hmm… no." Beckett grinned wickedly. "But I'm bored."

"Oh!" Castle acted incredibly wounded. "So that's all I am, Detective; something to do when you're bored? I feel so… so used!"

Beckett kissed him, long and hard. "Not that I mind it." He amended.

She smirked. "Our… 'friend' doesn't usually get in for another forty-five minutes or so."

"And you're bored." Castle added.

Beckett had the grace not to deny it.

Grinning, Castle swept his eyes over the crowd. "Would you mind if we used the bathroom?" He asked. "I don't trust alleyways. We could get attacked by sword-wielding vigilantes."

Beckett laughed at the inside joke. "Whatever you say, Castle."

They wound their way through the crowd, Beckett in the lead with Castle pressed into her back, his hands still on her waist as he gently pushed her in the proper direction. He saw, to his great relief, that they were a series of one-room bathrooms, rather than two large bathrooms with various stalls. Whoever designed this club had a pretty good sense of what couples got up to in there. Beckett entered the nearest available room and he followed, turning around to lock the door once it shut.

No sooner had the lock clicked than Beckett was on him, tongue and teeth and groping hands. Castle was momentarily startled but quickly got involved, running his hands up her smooth legs and tugging on her hair to get her head at a better angle for plundering her mouth.

"You weren't kidding." He managed to gasp out when coming up for air.

Beckett said something, but his tongue was in her mouth at that point so it really wasn't anything decipherable.

"What?" Castle asked, breaking apart.

"I said… oh never mind." Beckett huffed, un-tucking his shirt and frantically running her hands underneath it. "Just help me – ah!"

Castle took matters into his own hands – literally – by picking her up and spinning her around so that she was pinned between him and the door. Beckett made a noise of exasperation but braced herself on his shoulders to jump up and wrap her legs around his waist.

"Much better." She hummed, sounding like the cat that ate the canary.

"You have way too much fun with this." He said. He began to document every inch of skin on her upper body with his mouth. Beckett's hands came up to tangle in his hair, her grip with her legs becoming tighter.

"And you don't?" She retorted.

Castle was a little too busy exploring the right side of her neck just below her ear to reply. Beckett grabbed one of his wrists and turned it, peering at his watch.

"Twenty minutes, Castle." She warned him.

He stopped what he was doing to stare at her.

"You're the one who started this and now you're reminding me of our time constraints?" He asked, shocked.

Beckett ground against him. "I'll make it up to you later." She assured him.

Castle chucked as he helped her to lift up her dress. "I'll need you to get my pants." He told her.

"No problem."

It took a bit of maneuvering, but they managed to work together to get his pants down. "I haven't done this since…" Beckett's eyes flicked upwards as she thought back.

"Can we not think about you having sex with other guys right now?" Castle asked, only half joking.

Beckett smiled at him. "Of course." She reassured him. She took him in her hand and positioned him at her entrance. She pecked him on the lips. "This is much better, anyway."

He slipped in smoothly, careful not to get too erratic lest he bang her against the wall. Well, literally, not metaphorically. He was already doing that.

The setting – dirty bathroom in a club – and the fact that they shouldn't be doing this gave everything a raw feeling. The colors of the things around him were saturated, all noises muffled except for the sound of Beckett's harsh breathing and his own frantically racing heart.

"Castle!" Beckett's voice was hoarse and hot and rushed, a vocal version of the blood pumping through him as he thrust into her for the final time.

"Beckett…" He breathed when everything began to fade back to normal. Colors returned to their regular shades, the sounds of the club began to filter into the room, and… Beckett was checking his watch again.

"Six minutes." She declared as he helped her down.

"I love you, Beckett, but next time I'm taking my watch off and flushing it down the toilet." Castle warned her.

She grinned and kissed him on the nose. "Love you too." She said, moving to check her appearance in the mirror. She waltzed out the door to let him clean up. He took care of business, counted to one hundred, and then exited the room.

The suspect was confronted, the mission was a success, and the night was capped off with a debrief from their captain and a glass of celebratory champagne back at the loft.

Meanwhile, at the 12th, two junior detectives erased a recording that had been made before the suspect arrived. They then washed their ears with holy water from the church that the Irish junior detective attended, and vowed to remind their friends that they had to always, always, always turn off their hidden mikes before engaging in any… unauthorized activities on an assignment.

Like my series "You Have No Idea", this will be a series of one-shots where our favorite couple gets dirty while getting the dirt. If any of you have any suggestions, then please let me know! I would love to hear from you.

And yes, I got the bathroom stall idea from the fantastic glo1196, who also did a smut story set within a nightclub. She's always been a favorite of mine, so be a dear and check her out! (Not THAT kind of check her out… what are you, smut readers or something?)