Castle and Beckett sat across from an angry looking Bill Moss.

"Mr Moss," Beckett started. "Do you know why we brought you here?"

"All I know," he spat, "is I was in the middle of a meeting with an extremely wealthy potential client, when your buddies there came and ruined any chances of me closing a deal with them."

"I'm sorry if investigating the murder of your secretary puts a damper on your gaining new clients." Beckett glared at him.

He opened and closed his mouth a few times and then leaned forward, resting his elbows on the table. "Look, detective, I feel horrible about Anna Jo, she was a good woman, and a great secretary, but..."

"But she was more than just your secretary, wasn't she, Bill?" Castle asked.

He looked up, shock flickering across his face. "What? I mean I don't..."

"Give it up, Bill." Beckett moved in towards him. "We found the pictures. We know you were sleeping with her."

Moss ran a hand through his hair as he sighed. "Look, it's not what you think. We weren't just sleeping together. I loved Anna Jo, I wanted to marry her, got a ring and everything. But things were...complicated."

"Complicated how?" Castle asked.

"She has a daughter."

"We know, Billie Ann." Beckett nodded. "She didn't know her mom was even seeing anyone, was that the complication?"

He took in a deep breath. "It wasn't Billie we were worried about finding out."

"Then who?" Castle asked.

"Billie's father." He glanced around the room as if he expected the man to jump out at any second.

"You know who he is? Billie Ann said she didn't know who her father was." Beckett said, glancing pointedly at Castle.

"She doesn't know, and I wasn't supposed to find out either, but I did and now she's dead because of it."

"You think Billie Ann's father killed Anna Jo?" Beckett asked.

"I'm sure of it. He's a client of mine, and I know what he's capable of. Lets just say, it wouldn't surprise me a bit, knowing the things he's done."

"Who is this client?" Beckett's grabbed her pen and note pad.

"I can't tell you that. Attorney-Client confidentiality." He shrugged.

Beckett slammed her fist on the table. "Thats bullshit and you know it Moss! Attorney-Client privilege doesn't apply to crimes that your client hasn't been charged with yet, and if you feel your client is planning on murdering again, you have a duty to report it or be charged as an accessory. Now if you don't want to start looking for an attorney of your own, you better spill!"

Castle was always impressed with her knowledge of the law. It was times like these that he could almost picture her as a Supreme Court Justice. He shook his head as Moss started to speak.

"Ok, ok. I'm sorry. Look, I'd love to tell you, but if he finds out I talked, I won't need a lawyer, cuz dead men don't go to trial!"

He actually looked scared. Beckett leaned back a bit, "look, if you give us the information we need, we can protect you, but if you don't, he walks free and you know too much. Now what's it gonna be?"

He swallowed, looking around, searching for what to do. Finally he looked at Beckett and nodded, as she reached for her pen and paper. "So, Mr Moss, who is this client?"

He took in a deep breath. "You promise to protect me?"

"I promise." She nodded for him to continue.

"It's Bracken."

Beckett's eyes lit up. "Senator William H. Bracken?"

"Yes."

Beckett could feel her heart pounding in her chest. This was her chance, if he knew of Bracken's crimes, if she could get him to talk, she could put Bracken away for good.

Castle could almost feel Beckett trembling with anticipation. He needed to calm her down. If she got too excited and screwed this up, she'd never forgive herself.

"Bracken is Billie Ann's father?" Castle asked. Beckett turned and looked at him, she'd been so consumed with excitement she'd almost forgotten he was there.

"Yes."

Beckett took a deep breath. She'd been pissed when Castle first asked the question, but realized he was trying to keep her focused so she didn't press too hard and lose him. What would she do without her amazing partner? "How did you find out?"

Moss took a deep breath and wiped his sweaty hands on his pants. "About 8 months ago, Bracken came to me and asked for a favor."

"What kind of favor?" Castle asked.

"He asked me to give Anna Jo a job. I didn't really need a secretary, but he even offered to up my pay if I hired her."

"So she told you?" Beckett looked at him confused.

"No, I figured it out on my own. Not long after Anna Jo started working for me, Bracken came in to make some changes to his will. He added her and her daughter to it. When I asked him why, he told me to mind my own business, that he was taking care of a friend. Bracken always keeps a copy of his files in a safe deposit box as well, just in case. He and I have the only access to it. As I was filing the paperwork in the box, I noticed he had also set up a trust fund for Billie Ann. It seemed strange that he would suddenly take such an interest in this girl and her mother. Then I noticed the letter in the box."

"What kind of letter?" Castle was totally engrossed in this story.

"A letter to Billie Ann, to be given to her in the event of his death. I shouldn't have read it, but I couldn't help myself. It wasn't sealed, so I opened it. It was a letter explaining about the trust he set up for her, and that he was sorry he couldn't have been a better father to her, but it was safer for her if he wasn't in her life. I'd have to agree."

"What makes you say that?" Beckett was hoping this would lead back to the info she really wanted.

"Lets just say that Bracken has a lot of people who don't appreciate the way he does business."

Castle could feel the tension rolling off her body. They knew all too well about how Bracken conducted his "business" and they definitely didn't appreciate it.

"You said before that with his past, you wouldn't be surprised if Bracken killed her. What did you mean?"

Moss sat quietly for a moment thinking, "if I give you this information, detective, you have to promise me protection, and that you will make him pay for all he's done."

Beckett looked deep in his eyes, "Mr Moss, I can honestly say, that I can't think of any promise I would more gladly keep."