Amy should have known better than to trust Jake.

She stared at the glass on the wooden door, on which "Rosa Diaz: Private Detective" was written in fading print. The door looked like it had been broken, the building looked even worse, the entire neighborhood looked like a place where you would go if you wanted to be mugged.

This had to be some prank, Amy thought. Some joke on the new girl. Jake was a nice guy, and a pretty decent partner, despite the fact that he had barely any work ethic and his desk smelled like rotting cheese. Still, Jake wasn't above playing jokes on his coworkers, and Amy must have seemed susceptible to him, being the transfer.

"If you want to solve this, you'll have to see her." Jake had said at the office. His voice was low, deliberately trying to keep everyone else from hearing. "Rosa's a little...unorthodox, but she was a great detective at the Nine Nine."

Amy probably should have caught on when Jake said that. If he - the man who thought playing was better than solving crimes - thought Rosa was unorthodox, then she probably didn't exist.

Sighing, Amy turned to leave, only to hear a huge crash. It sounded like it came from inside the office. Immediately her muscles tensed up, and she perked her ears. One hand reached up to knock on the door, the other placed a hand on the gun concealed below her jacket. Just as her hand touched the door, a scream rang out.

Amy kicked the door open, drawing her gun. "Freeze!" The next second she lowered her gun in shock.

A tall, dark woman who could only be Rosa Diaz stood up, staring at her. On the ground, handcuffed and with two black eyes, was a whimpering man. Beside him was a crowbar, lying uselessly on the floor. The broken door suddenly made sense to Amy.

Damn it, Amy was the worst detective ever.

"Get me out of here!" The man screamed at Amy. "I did it! I killed him! I just want to go to jail where it's safe!"

"Ummm..." Amy looked from the man to Rosa, who was casually cleaning the blood off of her trench coat. It was black and made of leather, something that Amy couldn't but find daring and beautiful. She felt stuffy in her skirt suit by comparison.

"Please! Get me away from her!" The man screamed, drawing Amy's attention to him again.

"He killed Jeffery Peters for sleeping with his wife. And then broke in here and tried to kill me for solving the case." Rosa said, wiping the last dabs of blood off her coat. "Take him to the Nine Nine." She frowned. "Where's Jake? I thought he'd be here with you."

"I don't - I'm not - Jake's not here with me." Amy managed to stammer. "Wait, did he contact you?"

"Called me to let you know that he was sending someone over. Wanted to be sure I'd know you were telling the truth."

"Oh. Well, Jake said you could help me with a problem?"

Rosa raised her eyebrows. "Someone giving you trouble? Husband cheating on you? Need something taken care of that the police can't handle?" She flexed her hands, which still had drops of blood on them.

"What - no. I'm not even married." Amy managed. "I'm..." She looked at the man on the floor, who was staring from Rosa to Amy in a panic. "Maybe we should discuss this after I drive him to the station."

Rosa picked up the man by his collar and dragged him to the door, throwing him out onto the street. Then she slammed the door and turned to look at Amy. "He can wait."

"I -" Amy stared, still unsure if Jake had been playing a joke on her. This women couldn't really have been a police officer, could she? How the hell did she have the discipline to make it past week one of training?

"Listen, I've got about two cases of adultery and one mugging to solve." Rosa flopped down, casually cleaning the blood off of what looked like an ax. "So if you could get to the point, that'd be great."

Unnerved, Amy sat down on the edge of a chair. "I was assigned to a case the other day that...had an odd conclusion. It was a murder of one of the members of the 89th precinct found in the 99's territory, but it didn't add up. According to the report, he was out getting the groceries for his wife, and he saw a man trying to rob the store. He tried to arrest him, and the perp shot him and ran."

"That doesn't sound too fishy." Rosa said.

"Yeah, but when we found the perp, he claimed that he had been blackmailed. Someone told him to kill the officer because he had been investigating the wrong things. The blackmailer had the perp follow the officer and arrange to look like he was robbing a place. Then when the officer would try to stop him, he'd kill him."

"Who was the blackmailer?" Rosa said.

"The perp was shot before he could give the name. The detective who shot him claimed that it was because he was reaching for a weapon, but I was there andI don't think that was the case. And the person who shot him? It was Lt. Andrews."

Rosa dropped the ax. Amy felt pleased for a split second before the deadliest look that she had ever seen came over Rosa's face. She watched the already terrifying human being turn into something indescribable.

"Are you sure?" Rosa said.

"Positive." Amy said. "And...and I mentioned this to Jake because I wanted to investigate it, and he told me to go to you."

Rosa went over to Amy and crouched down in front of her. Amy tried to scoot backwards, but Rosa put her arms up on either side of Amy.

Oh God, Amy thought, I'm going to die here.

"If you want to investigate this, then you need to know that it's going to be the hardest fucking thing you've ever done in your life."

"I -"

"By accusing a police officer of murdering someone, then you'll be taking on everyone in the force who believes either he didn't kill the perp or was justified in doing it. You'll be taking on a bunch of sexist assholes who think that, despite this being the '40s, women shouldn't even be in the police force. You won't be safe. You won't get through this quickly. You might not even get Andrews, even if you have evidence, because his buddies will side with him. He'll get off scott free and you'll be fired. Your reputation will be gone, and you'll be known as the girl who didn't understand "men's police work"."

"I still want to do it." Amy said softly.

Rosa looked at her and nodded, then moved away. She sat down on the couch again, although this time her attention was fully fixed on Amy.

"Why?"

"Because it isn't right." There was a pause, in which Rosa looked skeptical. This wasn't winning her over. Amy decided to try again. "I have seven brothers who are officers, and risked their lives for the force. It should be more than some jackass who believes that he can get away with whatever he wants."

Rosa looked more interested.

"Because if I ever murdered someone like that, I'd be kicked out of the force in a minute. The fact that Andrews isn't because the boy's club of the force is protecting him is pissing me off. And...the fact that this isn't the first time he's done this." Amy looked straight into Rosa's eyes. "He framed you for murdering a criminal, and you were punished for it."

There was a moment of deadly silence before Rosa spoke.

"I was reporting my suspicions on Andrews for illegal activity to Internal Affairs when the shooting happened. He said that I was "too emotional" about arresting the perp and I shot him. After I left - after being told "I was suited in better places than the force" - the investigation into Andrews was dropped. Coincidence, huh?"

"If you don't mind my asking, how come you aren't in jail?"

"Holt saved my ass." Rosa said. "He knew he couldn't stop me from getting kicked out, but he knew he could save me from jail. Claimed that I was too nervous about arresting someone, and my "emotional state" needed to be considered because of my fragility. Said that I made a bad judgement call."

"I can't believe it."

"It was still pretty close." Rosa said. "If the Sgt. and Jake hadn't backed him up, I might have been looking at jail time."

"Jake backed you up?"

"He was my partner. Just like Holt, he knew I didn't do it." Rosa leaned forward. "That's why he sent you to me. He knows I still want to catch that fucker Andrews. And now you do too, apparently. But if we do this our investigation has to be kept quiet from everyone in the Nine Nine."

"Even Holt?"

"Especially Holt. He's one of the good ones, but the higher ups could lean on him to give you extra cases or more difficult work, if they find out you're investigating Andrews."

"I -" Amy felt uneasy. Yes, she knew taking on Andrews was going to be difficult, but she had at least thought she would have the Nine NIne backing her up. Being without them made her feel too exposed.

"The problem last time was that it was too public that I was investigating Andrews. That's how he was able to set me up. This time it has to be completely silent. If we do this, you tell nobody.

"What about Jake? I mean, he knows already. And he helped you out, so you know he's on your side."

"The higher ups have hopes for Jake. He likes the Nine Nine, but they're hoping that one day he'll "come to his senses" and leave for a different precinct. When you get back to the precinct, he isn't going to ask anymore questions. He knew enough to send you to me, and he knows that if he's involved, the investigation will be noticed. It's just you and me, kid."

Amy stared at Rosa. If she agreed to this, then she'd be investigating a crime with a crazy woman who had a grudge the size of Russia and a chip on her shoulder to match.

But if she solved this, then she could be huge. She would clean up the police department, they'd be able to get some actual work done instead of a web of corruption...

And if she made the rank of Captain, that wouldn't be too bad either.

She held out her hand to Rosa. The woman looked at it, smirked and grabbed it in her blood covered one, giving it a rough shake.