For all their concern about finding another lead to chase, their big break in the case is practically gifted to them just two days later, years of betrayal and bribes unraveling in the wake of one seemingly random murder, the victim left in an alley.

Again.

Ryan and Esposito were the ones who got the call and responded to the scene to find Orlando Costas and his lock picks, following up from there to track down the man's history with the Cazadores and his subsequent time in the military. They questioned his girlfriend and made little progress with her, though she gave them just enough information to help find the car Costas had been driving before he was killed and the phone he'd left inside. It wasn't until they figured out he'd been at Captain Montgomery's house earlier that morning that they reached out to Castle.

He's more than a little curious about how that conversation went, certain the partners he'd left arguing outside their precinct earlier in the week weren't suddenly doing backflips about his offer to help them with a clandestine investigation. Sure, he and Esposito had found enough common ground on which to stand while pushing an arson investigator too far, but Castle held little hope that their tenuous arrangement could withstand any real pressure. And Ryan, while probably far stronger than anyone gave him credit for, had seemed nauseated by the very thought of being caught by their captain. His reaction didn't make much sense for an NYPD homicide detective, but perhaps Catholic guilt ran that deep.

Regardless of why, or however reluctantly they opted to call him, he's on his way to meet them at Montgomery's house now, having bailed on his own partner with a lame excuse so he could hurry to speak to the widow of Beckett's former captain. When he arrives at the home, Castle ducks past the CSU techs working the scene and finds Ryan and Esposito talking to Evelyn Montgomery.

Slipping into place right behind the other two detectives – standing in a room Beckett cannot, but respecting the lead her boys need to take with this case – he hears Mrs. Montgomery explaining that she'd awakened to the sound of an intruder and walked in to find a man rifling through their filing cabinet. She further notes that she wasn't even supposed to be home, and the fact she was is both fortunate and not, but she was able to shoot the man in the shoulder just before he left with Montgomery's laptop and some of his old case files and notes.

Ryan and Esposito trade raised eyebrows and disappointment; Castle assumes they found only the dead thief, and none of the stolen information.

After winding their way through a few more questions and answers, the boys thank her and apologize for the trouble, asking her to call them directly if she thinks of anything more specific that might have been of interest to the intruder. It's mostly unnecessary given their understanding of the much larger picture, but she silently smiles her agreement before they turn for the door.

When the three men reach the sidewalk outside Montgomery's house, Castle finally speaks up. "I suppose we've all jumped to the same conclusion here?"

"Well, we can run Orlando Costas against Montgomery's old cases," Ryan suggests. "Maybe it's really as simple as a guy looking for revenge."

"By taking a laptop and files?" Esposito asks.

Ryan just shrugs, looking far from convinced by his own argument. "Looking for other names to go after?"

"Bullshit," Espo scoffs. "No way would that have ended with Costas dead in an alley immediately afterward. He was used by someone a lot higher up who ran a low-risk, high-reward game to get whatever information they needed from Montgomery's. It's about Beckett and her mom and dirty cops and shit that's gonna keep happening until we end it."

Castle shakes his head. "By why is this starting up again now? Beckett and Montgomery were killed months ago and nobody went after the files back then. You guys investigated, hit a bunch of dead ends, and these cases are still ice cold today."

Whatever look he receives from Ryan is fleeting, the detective choosing to watch himself kick at a couple of pebbles on the cement instead, but Esposito's glare lands hard. "Gee, I wonder what changed around here?"

There's no chance to respond, Castle left alone when Ryan and Esposito hurry into their car and peel away from the curb with a squeal.

"Of course they bailed on you, Castle. They have no real reason to trust you and the timing looks really fucking terrible."

Beckett is pacing his living room – again – angry and scared and more than a little hopeless. He's caught her up on the morning's events, ending with the admission that he may not be able to work his way back into the investigation. She's upset that Montgomery's family is dealing with any further fallout from her captain's mistakes, frustrated that she can't do anything to make it better. More than that, Castle thinks she tired of being stuck in his apartment, stuck in a world that's been done with her for a while now.

He needs to find a way to help her leave here, even if it's the last thing he wants.

"Okay, yeah, I get that. But I haven't done anything," he argues. "I mean, I obviously haven't done anything in the sense that I'm part of this conspiracy, but I haven't even done anything to help yet. Who cares that I read some case files and pissed off an arson investigator who knows absolutely nothing? Nobody's any closer to solving this, so why did the bad guys hit Montgomery's now?"

"I don't know. The boat hasn't been rocked, but someone's reacting as though it was."

"So, what do I do about it? I feel like we've been as smart about this as possible and we're right back where we started," he mutters. "And probably further back than that."

Her body rises and falls on a sigh. "Well, I'm open to dumb ideas now."

They're quiet for a long time before he finally turns toward her. "I think I've got one."

It's at least as crazy as it is dumb, but as Castle and Beckett wait for Ryan and Esposito to arrive at the apartment, Castle accepts that it may be their only chance to move forward. When he'd first suggested they confess Kate's presence to the boys, she'd laughed, hysteria stirred with a touch of tragedy and fear. She barely believed her own supernatural existence, even with the evidence at her powerless fingertips, so it seemed impossible that they'd convince two men who wouldn't be able to see her at all. Castle insisted she could offer up bits of personal knowledge about their lives – "Remember in the movie Ghost, Beckett? He said 'ditto' and it worked!" – but he's pretty sure she's been a skeptic for too long to be hopeful.

Still, she's standing beside him now.

Originally, he wondered if it might be better to meet the boys elsewhere for the big revelation; the familiarity of Beckett's former home had already aroused the suspicion Espo liked to haul around on his back and would likely encourage the paranoia Ryan has kept poorly contained. However, Castle's own anxiousness when he called the 12th led him to overcompensate with hospitality, and he ended up inviting the detectives to his apartment instead. Even more surprising than the words tumbling out of his mouth was Esposito's response that Ryan had already requested the chance to talk to them both, after hours and away from the precinct.

"I'm still not convinced about you, bro, but we might as well have it out at your place. We'll meet you there tonight."

So now Castle moves to answer the knock at the door as though he isn't about to tell two NYPD detectives the most bizarre ghost story they've ever heard. He smiles tentatively when the door swings open, nodding at Esposito's stiff greeting and waving a silent Ryan toward the couch. When Ryan drops onto the cushion and slumps forward, his head in his hands, Castle turns back toward Espo.

"What's wrong with him?"

"Looks like he's as excited to be here with you as I am," Esposito answers. "Though he insisted all three of us should be at this little chat."

Castle holds his hands in front of him in defense and resists the temptation to blurt out that there are actually four of them. "I get that you're pissed, but-"

"Stop right there. I'm gonna say a few things before Ryan does whatever he's doing, then you can go last. And I'm pissed at this entire situation, but you wouldn't even be included in this little conversation if I thought you had a direct hand in killing Montgomery or Beckett."

Ryan's looking up now and Castle glances toward Beckett before he nods for Espo to continue. "Our M.E. got a preliminary DNA match on skin found beneath the nails of Orlando Costas and it's the same as the DNA found from Beckett's shooting."

"So, Costas was definitely killed by the same person who killed Beckett." It's not a question and Esposito doesn't bother answering. And Castle doesn't dare look to his side now. "Have you told Captain Gates?"

"No way. But we hit a money trail and followed it back to the girlfriend. Finally got her to admit Costas got a call from someone he knew in the service, which backs up the military connection we guessed from the sniper shot that killed Beckett. She didn't have a name, but told us Costas met up with him at a church on State Street. And long story short, we got surveillance footage—"

"Churches have surveillance? What is this world coming to?" Castle feels three sets of eyes narrow at the interruption and he dips his head in apology. "Sorry, go ahead."

"I wanted to run our mystery man's face through the Army CID, but Ryan stopped me."

"Why?" Castle asks. "That seems like the fastest way to identify him, right?"

"He hasn't explained yet. Just put me off until you could be here, too." Esposito shifts his attention to Ryan. "So, now would be good time to fill us in. It's late and I'm tracking down this asshole tomorrow morning one way or another."

"No. You guys—" Ryan shakes his head and starts again. "We have to stop."

There's a long pause before Espo asks the obvious. "Stop what?"

"The investigation. We have to stop."

"Aren't we over this argument yet? I get that you're worried about crossing Gates, but with the Costas body drop, we finally have a solid lead to chase. We've kept the ties to Beckett quiet and we'll continue to work this like it's just a regular case. We've got it under control."

"No, we don't," Ryan argues. "They do. And if we don't stop now, they will kill us, Javi."

It's a simple statement, but Castle gets struck with a sharp chill, the kind alerting him to a situation that's about to get much worse. The slight tremble of Ryan's warning suggests Gates is the least of their concerns, and he thinks they're all bracing themselves for whatever else Ryan has to say.

"What's he talking about?" he hears Beckett hiss. Castle catches himself just before he responds to her directly, refocusing on Ryan and asking him instead.

Ryan stands up, scared of whatever lies beyond the walls of the apartment, but willing to face his partner head-on while Castle witnesses the carnage. "Before Montgomery went into that hangar, he sent a package to someone he trusted and it contained information damaging to the person behind all this. Montgomery was trying to protect Beckett, but the package didn't arrive until after she had been shot. Afterward, Montgomery's friend struck a deal with them. If they left the rest of us alone, that package and the information inside would never see the light of day. The only condition was that we had to back off. And that's the reason we're alive, Javi. Because we stopped."

"How does he know this?" Beckett whispers.

"How do you know this?" Esposito asks, fists hard at his side.

"In order for the deal to work, someone had to make sure nobody at the 12th pursued it. Not us, not Gates. Nobody else looking to take up Beckett's cause."

"Are you a part of this?" Castle croaks, earning another flash of anger from the three detectives in the room, even if two of them had secretly feared the same.

"I was just trying to keep us safe. This isn't a murder investigation anymore, they've turned it into a war. But then Castle showed up and all eyes are on us again. They know you guys went to see Halstead and this was their response. Montgomery's friend has kept us protected so far, but he said the deal's gonna be off if we don't stop now. It may already be off," he admits.

"We didn't need protection, we needed a lead and you sat on this for months."

Beckett mewls at Castle's side like an injured animal. "How the hell could he do this?"

"Javi, listen to me –"

"Listen to you? Why should I listen to you? How am I even supposed to trust anything that you say?"

Ryan looks upward, as though there's a better answer to be found than what he has to offer. "Because I'm your partner. And if that means anything to you, just stop chasing this thing."

"If it means anything? You're fucking kidding, right? You kept this secret from me. Stopped me from doing my damn job. From finding Beckett's killer. I loved her, loved Montgomery, and I thought you did too. This wasn't your call to make."

"Maybe, maybe not," he mumbles helplessly. "But I was just doing what I thought was right. I want to make it home to Jenny each night, and I don't want to lose my partner."

Esposito's laugh is laced with fury. "Well, you just did. I'm done."

There's really nothing to say after the door slams behind him, the walls rattling in protest. Ryan's expression carries guilt, frustration, sadness, and a touch of anger, but he only bobs his head for a moment before he shuffles toward the door with an apologetic wave and the mumble of something not meant to be heard.

It's only when Ryan is gone that Castle realizes he never had a chance to tell the boys Beckett was there listening, slowly shattered by every word.

Maybe it's better that way.

They're haunted by enough.

A/N: Thank you to those of you still on this ride with me! Things will be moving along pretty swiftly now; just a few chapters to go.