Here's a post-finale fic. As always, thanks go out to my betas (Anne and Ash) for helping me so much with this. Reviews and comments are always welcome.

Title: Unfinished Business

Chapter: 1 of ??

Disclaimer: The characters are not mine. Period. Please don't sue me.

Archiving: Just let me know.

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It had been one week since Sara last entered the CSI building, but to her it felt much longer.

Last week, after Grissom had taken her home, the two had a decidedly candid talk. With other people it would have turned into a major fight but Grissom and Sara were different. There was no yelling, but it wasn't needed. All the hurt of the past two years came out then and there.

Despite all that they had been through, the spark that had made Grissom call Sara four years ago when he needed her was still there. Fate had tried hard to extinguish it, but it had failed. Fate, though, had come mightily close.

An agreement had been made then. It had been unspoken, but it wasn't any less sacred. Grissom and Sara had agreed – for now – to set aside whatever romantic feelings they had for each other. For now, they would rebuild the friendship they once had.

Easier said than done, Sidle. Can you really put your feelings on hold again?

Of course you can. You did so for four years, right?

Yeah, and look where it got you.

Sara shook her head as she pushed the door leading to the labs. If it were any other man, she would have dumped him and torn his heart to pieces – much like she had done with Hank.

However, this was Grissom. Sara could never break his heart – probably because it would hurt her as much as it would him. Even in her darkest hours – the lonely days spent alone in her apartment, when nothing could wash away the pain – Sara had never, ever thought that her love for Gil Grissom was somehow, someway, misplaced.

And so, Sara let the pain that Grissom inflicted on her soul continue. The only balm was the knowledge that he was hurting worse than she was.

Sitting down on the bench in front of her locker, she leaned forward and rested her head on the cold metal surface. How could things between us have become so messed up?

Here's to making this work this time. Hopefully.

---

Gil Grissom had spent the last hour in his office. To an outside observer, he had spent the time just sitting behind his desk, eyes focused on the various objects inside the office that was his sanctuary.

However, the placid exterior hid a mind which was in turmoil. The phone call a week ago had bothered Grissom more than anything else in his life. Sara? DUI? No, that can't be her. She would never do something so stupid. It seemed like such a bad dream – except that it's true.

He closed his eyes as the thoughts came to his mind. I knew she was hurting. I just didn't know how badly until last week. If only I knew... so know what do I do. I don't know. I really don't know.

It's not hopeless. We both agreed to give it one more shot. That's all I can ask for right now.

Don't mess this up, Gil.

Grissom was still deep in his thoughts when the voice of Catherine Willows intruded into his thoughts. "Lost in your thoughts again?" Grissom looked up to see Catherine sitting in one of the chairs on the other side of his desk.

"Yes, Catherine?" There was a hint of annoyance in his voice.

"How long have we known each other?"

"More than ten years. Why?"

"Is there anything going on that we should know about?"

"I fail to see the point of this line of questioning."

Catherine sighed in frustration. "Sara, our resident workaholic, all of a sudden takes a week off. At the same time, you take three days off. Every day since then, I've found you before shift, in your office, sitting there lost in thought. Yet, you say nothing's wrong. Doesn't take a CSI to tell something is wrong."

"Catherine, even if something was wrong, it's... personal."

"You mean Sara."

Grissom stared coldly at Catherine. It was all the answer she needed, before she went on.

"Look, you may not think people notice, but they do. They can see you're miserable. They can see she's miserable. They don't know why, but I do. As a friend, Gil, I'm telling you, you've got to fix this. Otherwise, she'll threaten to quit. And this time, it'll be for good." By the time Catherine finished, she was standing, her hands on Grissom's desk.

He raised his head and icily glared at the blonde. This is none of your business, Catherine. This is between me and Sara.

Catherine's gaze dropped to the floor in surrender. "You're both hopeless, you know that?" she said.

Grissom didn't answer.

Catherine moved towards the door and left the room, shaking her head the whole time. The door slammed shut, leaving Grissom alone with his thoughts once again.

---

The Denali carrying Nick and Sara to their crime scene halted beside the coroner's van. Nick got out from behind the steering wheel and went to get their silver field kits. Meanwhile, Sara went to talk to Brass.

Several minutes later, Nick and Sara strode over to their crime scene. A resident walking through a park had noticed someone sleeping on a bench. Knowing that there was a homeless shelter a few blocks away the would-be Samaritan had tried to awaken him – only to realize he was dead.

The flashlights cut through the darkness as the two CSIs examined their victim. He was a male, with the unruly hair and beard typical of many of the homeless wandering Las Vegas. His head was propped up on one of the armrests – it was being used as a pillow. At first glance, it appeared to be a simple case of an alcoholic meeting a tragic death.

However, Nick and Sara were both trained not to trust appearances – their job was to carefully gather and analyze all the available evidence. It would either confirm the first impression or reveal a deeper truth. In this case, it was the latter. Sara noticed it first.

"Nick, if you were going to sleep, why would you put your hand under your body?" Sara said, gesturing with her flashlight towards the vic's left hand. It was pinned under his torso, as if it was hiding something.

"No way the vic put that hand there. Body was posed," Nick replied.

David, the assistant coroner, approached the pair. "You need any help?"

Sara turned. "Yeah. Vic's arm is under his body, and it's probably better if you guys give us a hand so we can see if there's anything unusual."

"Okay."

Sara moved out of the way as David and another person from the coroner's office lifted the body up just a bit. Nick was able to move the arm up to a more natural position quite easily – there had not been enough time for rigor mortis to set in.

When the hand came into view, Sara immediately noticed there was something loosely tied to one of the fingers. Without much effort, she was able to pull it off the hand so she could examine it more closely.

It was a clear plastic bag, not unlike what they used to bag evidence in. Inside was a postcard-sized picture of a waterfall; on the back was some writing. Sara gasped when she realized what it was. Nick, who had been watching David take away the body, turned immediately, a look of befuddlement on his face.

Sara noticed Nick's reaction. "I've seen this before," she said.

Nick was still confused. "A dead drunk or druggie on a park bench? Happens all the time."

"No, not that. This," she said while gesturing to the postcard in her hands.

He took a step towards Sara so he could clearly see what she was holding. "Postcard of a waterfall, in a plastic bag tied to the vic's finger. Has to be a unique signature. Where'd you see it before?"

She didn't miss a beat. "San Francisco."

---

Nick was walking from the morgue to join Sara in the lab. Robbins hadn't been able to find anything on their victim. They had a cause of death: cardiac arrest. However, they had no idea why his heart had stopped beating. No toxins had been found in his blood. The victim had been in reasonably good health, with no underlying health problems.

He found Sara examining a syringe they had found under the bench. Looking up, there was a tone of exasperation in her voice. "I hope you've had better luck than I have, because I have nothing."

"Cause of death is heart failure. Some bruising in the back of his neck, and a puncture leading to a vein in his neck consistent with a syringe. "

"Well, if he was injected with this syringe, I have no idea what it was. I've tried just about everything I know and all the tests have come back negative. As far as I can tell, the only thing in this syringe was air." She paused, suddenly realizing that she had all the pieces of the puzzle.

There was a special glint in her eyes. It was something that Nick had only seen on two people. Sara was one.

Grissom was the other.

"He died of cardiac arrest, Nick?"

"Yeah, why?"

"If someone did inject air into his veins, it could impede blood flow, leading to low blood pressure, arrythmia, and finally, cardiac arrest."

"He died from air in his veins?"

"It's certainly as plausible as death by chocolate, right?"

"You got that right." After a moment, Nick continued. "You told me you've seen the signature in San Francisco, but you haven't told me the details."

"Yeah, yeah, I was going to, but... I wanted to let Grissom know the details of it the same time you did."

"Okay. Have you seen him around yet?"

"No, but, I was about to look for him." After Nick gave her a questioning glare, she went on. "Alright, I was about to get him, okay?" She slid her stool out and moved towards the door. Turning to face Nick, she had her hands in mock surrender. "Okay?"

Nick watched Sara through the glass windows as she went off in search of Grissom. As he did so, there was one question in his mind. What in the world is going on between those two?

It was a question he had been asking for four years. He was no closer to an answer now as he was back then.

---

Grissom was just leaving the DNA lab when Sara came up to him. "We have a problem," she said.

You have no idea, he thought. Keeping a professional demeanor, he moved down the corridor with Sara following beside him. "What's wrong with your DB?"

"It's a serial." Grissom stopped in his tracks right next to the room where Nick was. Sara entered the room first, followed by Grissom.

Grissom spoke first. "Sara tells me you're dealing with a serial. Explain."

Nick answered. "Dead drunk on a park bench. Apparent OD, but tox screen came back clean. We also found a syringe, but as far as we can tell the only thing in it was air." He paused before continuing.

"We found this postcard tied to the victim's left finger." Sara slid the bagged postcard over to Grissom, as Nick continued. "It has a waterfall on the front. On the back, we have a sentence written on the back. 'Let the games begin.' Sara recognized it and said it was from San Francisco."

"Wait," Grissom said. "What was the cause of death?"

"Robbins says it was cardiac arrest, but gave no specific reason. Sara thinks the syringe was filled with air and injected into the vic's veins," Nick answered.

"Creative, but plausible. Go on," Grissom said.

"We had a series of crimes in San Fran just before I came out here," Sara said. "Just about everything – murder, rape, robbery, you name it. The only things in common were a postcard, just like this one, left at every scene, and the fact that we found zero evidence at every scene. We worked double, triple shifts – but it was still a dry hole."

"Ever give him a name?" This came from Nick.

"Yeah. The Waterfall Criminal, after the postcard he left at every scene."

"You should have called him Moriarty." Sara and Nick turned to face the source of the voice – Grissom.

He went on. "This isn't just any waterfall. Reichenbach Falls, in the Alps. In literature, it's where Sherlock Holmes and Professor Moriarty plunged to their apparent deaths."

Sara got it. "Our criminal thinks he's Professor Moriarty."

"The 'Napoleon of Crime', Holmes said of Moriarty. Able to outsmart all but the greatest detective in the land. The writing on the back means he's daring us."

"Daring us to do what?" asked Nick.

"To do what only Holmes was able to do," said Grissom.

"To catch him," said Sara.

"Or try."

---

To be continued...