If you're unfamiliar with the show Person of Interest, the premise is that a man named Finch has developed a computer program that analyzes New York City security video feeds and cell phone calls to identify crimes during their planning stage. The program identifies a threat and produces the social security number of the person involved. Two men, Finch and John Reese, a former CIA hit man, go about stopping the crimes before they happen. They have two cops who help them – Carter who helps because she wants to do what's right, and Fusco who helps because he owes Reese. Fusco refers to the network of dirty cops as 'HR.'

Reese swept the area, scanning all the surrounding faces, and Beckett and Castle both instinctively did the same.

"He didn't kill you because you weren't the target. Smith was his target. Do you want to keep standing out here where he can shoot you? He's quite the marksman, as you know."

Reese's calm was unnerving.

Beckett immediately stepped back into the alley while her eyes shot up to the surrounding windows. Castle placed his body in front of hers without even thinking about it.

"Can we go somewhere safer? I'll explain," Reese implored.

Beckett didn't trust this guy any further than she could throw him, but she didn't see any other choice. If he was telling the truth – which he seemed to be – then he might be their only way of getting out of this alive.

"Walk," she commanded.

Castle took her hand, lacing their fingers as though the connection itself would protect her.

"Castle? What the hell is going on? Talk to me, man!" Ryan's voice came through his phone, startling him. He forgot Ryan was still on the line.

"Could you hear him?" Castle spoke into the phone again.

"Yeah. What do I do? Esposito's not talking to me, but if I text him, he'll go. And I can try to get Gates to send a protection detail."

"Do it. Espo & a cruiser. Make sure they're solid."

Reese started walking, and they followed. He watched the crowd and the windows above carefully but still managed to look like a sight-seer instead of someone who is paranoid. Paranoia keeps people alive when they're being hunted.

Castle and Beckett tried their best to not look hunted and to keep scanning faces as well.

As they stepped into her building, Castle could hear Kate breathing too fast. Terror was on her face, but she kept walking. So he did, too. Reese cleared the stairwell then the hall, then her apartment, before she entered any of them.

She pulled her gun from the drawer as soon as she walked in while Castle shut the blinds. Reese leaned against a bookcase. He noticed the huge painting of the woman running through an air raid and wondered if Beckett chose it because that's how she feels.

"Nice place." As if they wanted to chit-chat.

"Talk." It was Castle growling the command this time. "Why is she a target now when he could have easily killed her a week ago?"

He tried to ignore the squeeze around his heart when he spoke those words. Kate was still acting alarmed, but at least she wasn't having a panic attack.

Reese nodded. No small talk. "Maddox is a professional. If he was hired to find Smith and kill him, he wouldn't complicate things by killing you."

"He threw me off a roof!"

"If he intended to kill you, there would have been no way for you to have made it. He didn't track you down, you hunted for him. He could have killed you and Esposito in his hotel room. He ran instead. He could have shot you on the roof. He fought you instead. He could have killed you in the fight. He flung you instead. He could have kicked you off the ledge. He walked away instead. See, to him, you falling because you lost your grip and couldn't climb back up wouldn't have been his fault; it would have been yours."

"Hers?" Castle hissed. "Her fault? Listen, you bastard, I don't know who you think you are, but-"

Kate laid her hand on his arm, quieting him with a look. "He's right. It would have been my fault. You told me so the day before. You knew I would go after him and be reckless and get myself killed."

She seemed amazingly calm. "I'm sorry, Castle," she whispered. She worried her lip between her teeth, knowing he had forgiven her; but she hadn't yet forgiven herself. "I should have listened to you."

He didn't have an answer for that. He just nodded and focused again on the stranger in the room.

Reese continued as though he hadn't been interrupted. "Smith is dead. His contract job is done. He's been paid. But my intel says he's coming after you now. Which probably means you pissed him off, so he simply wants to kill you."

"He wants to kill me," Kate murmured, looking at the floor.

"He's probably never gotten that close to getting caught before." Reese shrugged. It was the best reason he had to offer.

Beckett sat on the arm of the couch, gun still in her hand, and silently wished she'd done it all so differently.

Xxxx

A loud banging knock at the door startled them; Reese pulled his weapon; all three jumped and hustled to get their backs against walls, Reese and Beckett both held their guns at the ready, trained on the door.

Another series of bangs rattled the pictures on her wall.

Xxxx

"Beckett! You in there?" Esposito screamed.

He didn't answer the phone when Ryan called, but the text seconds later that said, "becketts place 911 now," had him grabbing his gun and jumping in his car. He at least had the courtesy to text back, "on it."

He raced over to her apartment, hoping to not be too late, to not find her in a pool of blood. Damn that woman.

He was about to kick in the door when he heard a quiet, "It's Espo. Thank God," and the locks clicked open.

"Kate? You okay?" He glanced at her, instantly registering her lack of bulletholes, and immediately stuck his head in to survey the apartment. Castle. And some serious looking guy in a really nice suit.

"Yeah. We're fine. Ryan sent you?" She opened the door enough to let him in, then bolted it behind him.

He nodded curtly. He didn't holster his weapon since she and the suit were holding theirs. He jerked his head toward the guy in the suit, silently questioning.

"He claims to know Maddox, and that Maddox is coming after me."

He eyed the stranger suspiciously. "So what do we do?"

"First step: I call my partner." He pressed the button to connect with Finch.

Xxxx

Ryan set up a cruiser to be parked outside Beckett's place, but it didn't make him feel any better. He kept wringing his hands, thinking about "The Discourager," Castle's cop character in Heat Rises that was supposed to be keeping Nikki safe, but ended up being the one who tried to kill her.

He sagged in his chair and sighed and decided to text Javier to make sure he had Kate & Rick's backs. As if that had done a lot of good a week ago.

A/N: Please review! I'm addicted to reviews like Lindsey Lohan's addicted to everything else.

Next chapter: more Caskett & more of the other characters.