Disclaimer: The only part of Castle that I own is the TV on which I watch the show.

The Andes. The freaking Andes. Just for once couldn't Josh administer aid to people desperately in need of it at home, and not an eight-hour flight away? There were plenty of them right here in Manhattan. Or the South Bronx. Or Camden, New Jersey, if he insists on going to another state. If he's hellbent on the mountains, why not the Appalachians?

He was supposed to come home ten days ago. Then he delayed it, and delayed it again on Wednesday, when he'd texted that he'd changed his flight to Saturday. Today. The only good thing about all this is that it's solidified her decision to part ways with him. She's mentally written what she's going to say when she sees him. His plane landed almost two hours ago–she'd checked it twice online–but she still hasn't heard a peep from him. If Castle were returning to the city from somewhere, anywhere, he'd have texted her at least five times by now. She can imagine them popping up on her phone every few minutes.

"Plane's at the gate. B13. Isn't that a Bingo number?"

"This terminal is insane. Is there a secret holiday that I don't know about?"

"Have you noticed that a lot of people suddenly have orange suitcases?"

"In a taxi headed home. I hope. The driver is taking unknown side streets of deepest Astoria. You may have to come rescue me in a squad car. Lights and sirens."

"Did you miss me annoying you?"

If he really had sent that last text, she'd have said yes. Or maybe no, to see how much he protested that she really had. And if he were lost in deepest Astoria? Damn right she'd rescue him, lights and sirens.

But her phone has remained silent. She's jittery, so of course she makes coffee, and on her second sip she hears a knock. When she looks through the peephole she sees a familiar face with a two-week beard. What the hell? She yanks open the door.

"Josh?"

"Surprise!" He brushes by her, dumps his bag on the floor, and envelops her in a hug.

She loathes surprises and he knows it. "Hi."

"Happy to see me?"

"Of course." That should be a three-word sentence, with "not" at the end, because she's ticked off at him. "How was your trip?" she asks, breaking away from the hug. He's yammering away about Peru as he walks to the sofa and she trails after him. He extends his legs, props his boots on the coffee table–something that's always irritated her, and why hadn't she told him?–and keeps right on talking. She drops in with the occasional "mmhmm," "wow," or "really" until he finally looks up at her and pats the seat next him.

"Sit down with me, Kate. I haven't seen you in ages."

Yeah, no kidding. No "How are you?" or "I missed you." There's no point in sitting down when she wants to get this over with right now, before she loses her nerve and her break-up script deserts her. Besides, standing gives her an advantage over him, which is what she needs at the moment.

"Listen, Josh?"

His smile recedes. "Yeah?"

"It's fantastic what you're doing. Helping people in terrible situations. It is. I admire you for it. But the thing is, you're never here."

"Jesus, Kate, I'm–"

"Please, let me finish. I understand that you have to be away, you're compelled to be, but I need someone who can be around more. Your job is wildly stressful, but so is mine, and I need someone I can de-stress with, you know? You and I are perfect examples of ships that pass in the night, but I need a safe harbor, too. Sorry if that sounds corny." Shit, is this lame? If she'd rehearsed this out loud she might have realized it. She presses on. "I don't regret any of our time together, but it's not enough. And you should be with someone who doesn't need what I need. You deserve that."

"So, this is it?" His mouth is twitching even after he's finished the question. She can see his muscles tightening, from jaw to thighs. "This is it? Your goddamn welcome home speech? You can at least be honest, for Christ's sake. You owe me that."

"I am being honest."

"Bullshit." He gets to his feet, his face purpling. "What was it that sealed the deal with you and Castle, huh?"

"There's no deal between Castle and me."

"Bullshit again." HIs voice raises several decibels. "While I was in Peru doing something really important, and the two of you were in Los Angeles working on that case–"

She hears contempt when he says "case." He almost spits the word out, as if it were worthless, as if what she does is worthless.

"Did he work on you then? Use the time and place to work you up in bed?"

That she hadn't expected, and she feels as if she's been punched in the stomach. "Not a chance." She's afraid her voice is unsteady.

"If I look in the bathroom, will I find his aftershave on your sink? Will I? If I sit on your bed will I smell it on your sheets?"

She's not unsteady now, she's furious. "Fuck you, Josh."

"Fuck me?" He's leaning in, his face so close that she can feel his breath and see the tiny tic he can't control at the corner of his eye. "Fuck me? Not while you're fucking Castle."

She's already deviated from her planned speech, and now she does something that she's never done to anyone. She slaps him hard across the face. "Leave. Now."

A moment later he slams the door so forcefully behind him that the vibration knocks one of her favorite mugs onto the floor and it shatters. "Worth it," she says later, as she sweeps the shards into the dustpan. It's only 9:30, but she goes to bed. She's relieved to have severed ties with Josh, but his reaction was so unsettling and vituperative that she's exhausted.

It's the longest, soundest sleep that she's had in years, and she's grateful not to be heading to the precinct but driving upstate to pay her weekly visit to the hit man known as Hal Lockwood. The hour-plus trip lets her mull over last night, and consider what she should tell Castle and when. Maybe she'd been naive, but she'd really expected the conversation with Josh to be straightforward, even calm. There'd never been any commitment on either side. But in the light of day–and it's a beautiful May morning–it occurs to her that Josh is used to getting his own way. His altruism runs deep, but it's limited to his professional life, not his personal one. He's also a surgeon, and like many surgeons, he always assumes that he's right.

The exit for the prison is half a mile ahead, so she flicks on her blinker and changes lanes. Maybe she'll get something out of this son of a bitch Lockwood today. She's been coming here for months, trying to get him to lead her to her mother's killer. Maybe it's the spring weather that's making her optimistic, but she thinks that she's close now. Maybe she'll finally break him this summer, and then she can let her heart break all the way open, and invite Castle in.

She parks in the prison lot and goes inside, only to learn from Officer Ryker, who always greets her, that Lockwood has just been moved from his high-security, restricted cell to the prison's general population. Her quiet day explodes. Minutes later she and several guards find Lockwood standing over the body of Gary McCallister, whom he had just shanked. McCallister, one of the crooked cops who had helped frame Joe Pulgatti and thus contributed to the death of her mother. McCallister, the man who told Castle and her that they had woken the dragon. As she looks at Lockwood's blood-soaked hands, it occurs to her that the dragon is more than awake now: he's howling, and she's glad. She's that much closer to closing her mother's case.

But then morning turned to night, literally and metaphorically. That's all it the time it had taken, a half-rotation of the Earth on its axis, to destroy her hope. That evening, she and Castle had gone to Lockwood's arraignment because she'd wanted to poke the dragon again. The proceedings should have been quick and straightforward; afterwards, maybe she'd ask Castle out for a drink, inch forward a little. It hadn't happened. None of it. In the flash of a grenade, Lockwood, assisted by men disguised as cops, was uncuffed and on the run. By the time she'd made sure that Castle was uninjured and chased Lockwood to the roof, he'd been taking off in a helicopter. She'd emptied her gun, and knew that a least one shot had hit the chopper, but it hadn't made a difference. After that, she'd sent Castle home, filed a report, and gone to her apartment. Sleep had never come and at four she'd given up, taken a shower, dressed, and gone to the precinct.

Discouraged as she'd been, she'd kept at it. New evidence indicated that McCallister was merely the means for Lockwood to escape, and his real target was still at large. It hadn't taken long for her and Castle to figure out who it was, in theory: the third bad cop. The X side of the Raglan-McCallister-X triangle. The one who knows who's behind the killing of Johanna Beckett, and is therefore a danger to the boss. If only they knew who either mystery man is. She'd briefly been hopeful when the New Jersey state police had found the stolen helicopter that McCallister had used, but had fallen back into a pit when she'd discovered that it had been thoroughly cleaned with bleach. No DNA had survived. Another dead end. She'd said good night to Castle and the boys at the hangar and gone home, as despairing as she'd ever been.

Things had gotten worse today. Ryker, the sweet guard at the prison who'd always joked with her and put her at her ease, had been found murdered. He hadn't been so sweet after all: up to his neck in debt, he'd taken $50,000–untraceable, and routed to his bank through Dubai–to arrange Lockwood's transfer at the prison. And then he'd been shot in the head, at home. Ryker had been another pawn sacrificed in this sick high-stakes game. She knows the chess master is that third cop. She knows it. Ryan and Esposito don't believe her, but she doesn't care. She's right, and she demands that they keep looking. For the third night in a row she goes home in a bleak mood, but this time she's also furious.

xxxx

Scowling in the mirror of the men's room at the precinct, Castle is berating himself for insisting that Beckett can handle the pressure of the case. He'd wanted to believe it, still does want to, but he knows that she's strung so tight that she's about to snap. Last night he'd had the most surprising unannounced visitor of his life. Jim Beckett. "This man she's chasing," Jim had asked, his face etched with anxiety. "How dangerous is he?"

"He's a trained killer." Way to go, he'd thought too late; don't sugarcoat it. You could have been honest without being so blunt. It's hard to imagine the hell that Jim has gone through, and the fresh hell he's facing. If Alexis is 15 minutes late getting home, he wants to start calling hospitals–almost had, on a couple of occasions. And what is that in comparison to what Jim has to live with every day?

"What happens when she finds him?" Jim had asked. "I've already lost my wife over this." It had been the desperate appeal of one father to another, Jim clearly suspecting–and rightly so–that Rick is in love with his daughter, Kate. "Don't let her throw her life away."

Jim wanted him to get Kate to stop this suicidal chase. Simple as that. But not so simple, because Beckett is the single most complicated person he's ever known. And private. And stubborn. Still, he'd had all day to do something and he's done nothing. They'd been very busy because of the murder of the prison guard Ryker, but he'd had ample opportunity to pull her aside and say something. He hadn't. Later, when she'd borne down on the third cop theory and Ryan and Espo had challenged her, he still hadn't done anything.

"We went through everything," Espo had said. "We looked at every cop we could find who could've worked with them. None of them are our third guy."

"Well, then check it again. And when you're done with that, check it again." She'd been crackling with rage.

Then Ryan had made the mistake of saying, "Beckett, we want him as bad as you."

That had put her over the edge. "The hell you do. Nobody wants him as bad as I do, okay? Nobody. So, check it again." With that, she'd stormed home, her bag overflowing with case files.

He should have gone after her, but he hadn't. Instead, he'd stayed late with the boys, going over and over and over things. He'd called her several times, but she'd never responded. When Espo had asked him how she was, he'd said, "She'll be fine. She always is."

The hell she was. The hell she is. Why had he kept insisting that she's fine? Because he's a coward. Because he doesn't want to face the truth that she's soul-deep in her mother's case again, and in danger, because he'd sent her there. Because he doesn't want to face her and have her turn on him, because that's exactly what she'll do.

The only upside, and it's important, is that by chance–thanks to the improbable combination of a cold beer bottle on and his knowledge of old typewriters–he and the boys had found doctored police reports that should be an enormous help in ferreting out the third cop. They'd showed the captain, who'd authorized Ryan and Espo to get on it. Castle, however, had stayed behind to talk to Montgomery, who'd put a protective detail on Beckett and assured him that they were good.

"Good enough to stop Lockwood? Look, she's not gonna stop, and the next time he sees her, one of them is gonna die. Take her off the case." He'd had the balls to demand that of the captain, but not enough to run after Beckett.

Montgomery had filled him in on his history with Beckett, how he had known from the very start that nothing he could have done would have stopped her looking into her mother's murder. And then he'd shocked him even more than Jim Beckett had 24 hours earlier by saying, "I cannot make Beckett stand down, Castle. I never could. And the way I figure, the only one who can is you."

That's what had driven him here, to the relative quiet of the men's room. "Man up," he tells his reflection. "Kate Beckett's father and the man who has been like a father to her are putting her life in your hands. Move your sorry ass and go make your case." He splashes some water on his face, pats it off with a rough paper towel, and puts on his mental armor.

As soon as he enters Beckett's apartment, he lets her know about the developments in the case. She bristles, and asks why he hadn't just phoned her. It's a reasonable question, and when he hesitates, she ups the bristliness to near hostility, holding her gun at her side.

"Castle, if you got something to say, just please say it."

This time he doesn't stall. "Beckett, everyone associated with this case is dead. Everyone. First your mom and her colleagues, then Raglan, then McCallister. You know they're coming for you next."

When she counters that there's a protective detail on her, he tell her it's not enough. "I don't think we're gonna win this."

That doesn't sit well.

"Castle, they killed my mother. What do you want me to do here?"

"Walk away. They're gonna kill you, Kate. And if you don't care about that, at least think about how that's going to affect the people that love you. You really want to put your dad through that? And what about Josh?"

Maybe it was mentioning Josh that did it, but now she's barely suppressing her rage. "And what about you, Rick?"

Oh. Oh. He hadn't expected that, and he fumbles. "Well, of course I don't want anything to happen to you. I'm your partner. I'm your friend."

"Is that what we are?"

He can't take this back and forth anymore, this too-careful speech, so he takes off the filters and the gloves. "All right, you know what? I don't know what we are. We kiss, and then we never talk about it. We nearly die frozen in each other's arms, but we never talk about it. So, no, I got no clue what we are. I know I don't want to see you throw your life away."

Each time she withdraws or turns away, he goes after her, closes the physical gap between them.

"Yeah, well, last time I checked, it was my life, not your personal jungle gym. And for the past three years, I have been running around with the school's funniest kid, and it's not enough."

If she'd thrown acid on his face it wouldn't have hurt the way that had. He won't let up. "This isn't about your mother's case anymore. This is about you needing a place to hide. Because you've been chasing this thing so long, you're afraid to find out who you are without it."

"You don't know me, Castle. You think you do, but you don't."

Another shot of acid, one that penetrated his skin and entered his veins. "I know you crawled inside your mother's murder and didn't come out. I know you hide there, the same way you hide in these nowhere relationships with men you don't love." Oh, Jesus, maybe that was too much. He has to soften this a little, soften what he's saying to the woman he loves so that maybe she'll listen to him. "You could be happy, Kate. You deserve to be happy. But you're afraid."

It doesn't work.

"You know what we are, Castle? We are over. Now get out."

When he runs down the stairs of her building and out into the night, he can hardly breathe. He leans against the wall and gasps as he tries to process the destruction, in the course of a couple of minutes, of what they'd somehow stitched together over during the last three years. "Our first fight," he says. "Our first goddamn fight and that's it. It's over. It's over and the next time I'll see her she'll be in a coffin." He staggers to the curb and throws up into the gutter.

The next thing that he's aware of is the sharp voice of his mother. He has no memory of how he got home, or what he's done since he got here.

"Oh, my God! What the hell's going on here?"

It must be very late because she's in her dressing gown, and apparently he had just drained a glass of Scotch and thrown it at a large mock up of Heat Rises. He can taste the alcohol in his mouth, along with the bile, but he and she sit down for the kind of mother-son conversation they should have had a long time ago. He admits his anxieties about Beckett, and she tries to calm him. He persuades her to go back to sleep, and he goes to bed soon after, though not after another 50-proof infusion.

As soon as he's awake the next morning, he calls Beckett. She'd thrown him out last night, but he's not going to be dissuaded from trying to get her to step back from the investigation. It's his debt to her father, to her captain, and to her. He phones every ten minutes, and every single time she declines the call. Staying at home is driving him wild, but he can't, won't, go to the precinct. By dinnertime–not that he has any appetite for dinner, and he's relieved that Alexis is staying at a friend's to study for finals tomorrow–he's lost count of how often he's called her. It must be 50, at least.

He jumps when his phone rings: it's Montgomery. The captain sketches in the events of the day, says that they might have a lead, and follows that with an odd request. He wants Castle to meet him at the hangar where the stolen helicopter had been found. "Come now. And don't tell Beckett," he says.

"I can't. She's not speaking to me."

"So I gather. We need to keep her out of this. Just meet me there, but stay out of sight, all right? I'll shout out to you when I need you. Got it?"

"Uh–"

"Got it?"

"Yessir."

On the way to the hangar he calls Espo and Ryan, but gets only voicemail. He texts Ryan, asks what's up, and gets a reply. "We're out on a lead. Trying to track down 3rd cop. Later." A quarter of an hour after that he's standing in the shadows on the far side of the hangar. He can hear Montgomery and Beckett talking, but he's too far away to make out what they're saying. Why is she here? Wasn't the point to keep her out of whatever the hell is going? It's a May evening, but he feels as cold as he had in the back of that truck with Beckett months ago. He feels as if there's ice between each of his vertebrae.

"Castle!" It's the captain. "Get her out of here."

He steps into the murky light, sees Montgomery holding a gun and Beckett looking as if she's a second away from tears.

"Captain, I don't–"

Montgomery cuts him off. "Don't argue. That's why I called you. Get her out of here, now!"

There's an SUV in the distance, headed for them.

He's never seen or heard Beckett like this. She's pleading with Montgomery, telling him repeatedly that she forgives him. For what? What is there to forgive? She keeps telling him he doesn't have to do this. Do what? He feels lost and helpless, but when Montgomery barks at him again to get her out, and he lifts her up and carries through the door. She's crying and screaming the whole way, flailing and kicking her legs against him. He hears car doors opening and closing, and a series of footsteps. Three people? Four? He realizes that it must be Lockwood and his posse. When he and Beckett are safely out of sight, he puts his hand gently over her mouth, shushes her, and lies as he tells her again and again, "Everything's okay. Everything's all right," when it patently isn't.

Lockwood is loud enough for him to hear, and he's demanding to know where Kate is. Montgomery doesn't yield. A moment ago he'd told her, "This is my spot. This is where I stand." In Castle's head he's screaming, "What did you do, Roy? What did you do?" And what is he doing now? Sacrificing himself for Beckett? Why?

And then it hits him. If he was cold before, he's frozen now. The third cop. It was Montgomery. Roy. He'd have been a young man then, maybe had a new baby. Just starting out. Needed money. He's atoning, his life for Beckett's. His life for her mother's life. But Beckett forgives him, as she'd forgiven Royce-except the stakes are so much higher here. The highest. She doesn't want this, doesn't want Montgomery's blood on her hands, because that must be how she sees it. She just wants Lockwood and his master. No wonder she's inconsolable. He hears shots, then silence, shots and more silence. Whatever happened is finished. He releases her, and she races out. He stares after her at the carnage. No one is moving except Beckett, who is sobbing over Montgomery's body, her forehead pressed against his chest.

As he approaches quietly, not wanting to intrude on her private grief but aware of the need to get them both away from the scene, he sees a cell phone, screen side up, on the concrete. It's hers. She must have dropped it when she confronted Roy. He picks it and reads the text that had arrived a few minutes ago. It confirms his sickening epiphany: "3rd cop-It's Montgomery!" After pocketing the phone, he hastily concocts a credible story, in case they can't slip away in time, about why he and Beckett are here. And then he phones the boys.

Over the next four days, he, Beckett, Espo, and Ryan stitch together their story and sew it up tight. Montgomery will have died a hero. "We owe it to him," Kate says when they're gathered in her living room. "All of us." No one disagrees.

At first there is a fragile truce between him and Beckett, but she begins to lean on him more each hour. Each freighted hour when they deal with interrogations and funeral arrangements and making sure that Evelyn Montgomery and the children are looked after. It's Evelyn who asks that Beckett deliver the eulogy. "Of course," she says to the widow. "Of course I will. Of course. It will be an honor."

The weather is perfect on the day they come to bury their captain. Blue sky, bright sunshine, a puff of a breeze. He wishes that there were thunder and lightning and hail, God–if God really exists–making his wrath evident. After he and the other pall bearers lay the flag-draped coffin on the stand at the grave, his partner walks towards the podium. Montgomery's widow is weeping over the folded flag, now a tight triangle in her hands, and Beckett begins to speak. She looks so frail, but steadfast, as she talks about her mentor. The captain, she says, believed that "there are only battles. And in the end, the best you could hope for is to find a place to make your stand." She looks at him as she says that, eyes bright under the visor of her cap.

Resolved not to break down, he looks away from her and sees a glint in the distance, a tiny flash that seems to be coming from a row of tombstones. It's a gun. It's light bouncing off the stock of a rifle. He throws himself at her at the same moment that he hears the pop of the gun.

"Kate!"

The impact knocks the cap from her head, and they both fall to the lush green grass. The green grass that should be as black as the mourning clothes he's wearing. Green is for hope, and there's nothing hopeful here. Kate has taken the bullet. She looks stunned, but she doesn't make a sound as he cradles her head, horrified as he notices her white glove covered in blood.

"Kate, please. Stay with me, Kate. Don't leave me, please. Stay with me, okay? Kate, I love you. I love you, Kate."

She can see Castle, his face just inches from hers. She can hear him, too, but she can't respond. He told her that he loved her. It's the first time he's told her that he loves her, and it's the last thing she'll ever hear. The last thing, because she's been shot in the chest, and there's no surviving that. The pain takes over and she closes her eyes. It's the end.

TBC