Chapter 1

Aaron Hotchner looked up at the sound of knocking on his open office door, carefully composing his face to hide his frustration. He'd been focused on the files resting neatly on his desk. Only a few more documents to review and he could officially close their latest case. It was midmorning in DC but he'd told the team that if they finished their reports they could take an early day. The interruption created an unpleasant delay.

At the sight of Morgan hovering in his doorway, Hotch felt his irritation drain away. The normally nonchalant agent appeared tense. Morgan stood with arms crossed and jaw clenched. His eyes were dark and made Hotch cautious.

"Can I help you with something?" Agent Hotchner asked.

Morgan hesitated before speaking, eyes darting briefly back out the door as if reconsidering his decision to speak to Hotch.

"I need to request some time off," Morgan said at last.

"You are due for some PTO. That shouldn't be a problem." Hotch knew better than to pry when it came to this particular agent. If Morgan didn't want to discuss his strange behavior, no prompting from his boss would change his mind. Hotch did ask one question. "How long will you be away?"

"I'm not sure."

Hotch continued to stare. His silence paid off as Morgan took a step farther into the room.

"I need to help an old friend in Las Angeles. It could take up to a week or longer."

"Take as much time as you need," Hotch said. When Morgan didn't leave immediately, Hotch asked, "Is there something you need from me?"

"My friend wants me to help him locate a missing person."

Suddenly understanding, Hotch said, "Close the door."

Thirty minutes later, the team assembled in a conference room, all with drooping shoulders and tired eyes. They had hoped to catch a break after their last case. The team hadn't even been to their homes since stepping off the plane early that morning. But this case couldn't wait.

Hotch briefly caught Morgan's eye and nodded. The agent returned the nod and Hotch addressed the room.

"Thank you for meeting," Hotch said by way of opening. "I understand you are all tired, but we have a situation. Morgan?"

The dark agent got wearily to his feet. "I got a phone call today from an old friend, Agent David Sinclair. He works for the Bureau out of the LA office. He asked for my help locating a missing person."

"That's my que," Garcia chirped. Her words were followed by the clicking of a keyboard. The projector lit up and a photo of a man with dark curly hair appeared on the wall.

"Dr. Eppes?" The response came unexpectedly from Reid.

"You know him?" Morgan asked.

The young man's voice held respect bordering on wonder. "We've never met in person. He started teaching at CalSci the year after I graduated. He's one of the top minds of the century. He's a brilliant mathematician. He developed the Eppes Convergence when he was still a teenager. And he's a recipient of the Milton Award."

Though most of the room didn't understand the specifics of what Reid described, hearing this praise come from their resident genius made the rest of the team looked at the photo with more admiration.

Hotch cleared his throat. "Dr. Charles Eppes went missing two days ago. After Agent Sinclair contacted Morgan, I made a few calls. We've been officially assigned to help find him."

"Why would we be asked to help find a missing mathematician?" Emily asked.

"He's not just a mathematician," Rossie answered. "He's a consultant. I thought I recognized the name. Agent Don Eppes is SAC of the LA office. Dr. Eppes is his brother. He often helps him with different cases."

"How do you know that?" Emily asked.

Rossi shrugged. "I've read reports."

"He doesn't just consult for the FBI," Hotchner interrupted. "The NSA, CDC, and other agencies have called him in to help on classified projects. His high security clearance is the reason we've been asked to help find him. Until we know the location of Dr. Eppes, we have to assume the situation is a threat to national security. Wheels up in thirty."

- O -

Don leaned over his desk, resting his head in his hands. He took deep breaths, forcing back the pain, the panic. It had been two days since Charlie disappeared. Two days, and not a single lead.

He thought back to the fateful phone call from this father.

"Eppes."

"Donnie? Have you seen Charlie?"

Don hoped his father couldn't hear his eyeroll over the phone. "Not lately. Why?"

Alan's voice held a note of concern. "He was supposed to help me clean the koi pond this afternoon after class, but he never showed."

"Well, Dad, you can't blame him for wanting to get out of scrubbing pond scum off rocks." Don's attention wandered back to his computer and the report he was in the middle of typing.

"Then Larry called asking why Charlie skipped class."

Don sat up. That caught his attention.

"That isn't like Charlie," he said into the phone.

"No. It isn't. You're sure you haven't seen him?"

"We didn't need him on this last case. Besides, with finals around the corner, he's been limiting how much time he spends here."

Alan sighed into the line.

"Look, Dad, he probably got caught up in some math equation somewhere and lost track of time. You know how he gets. Tell Larry to check his office at CalSci again. If he isn't back by tonight, call me."

Don remembered the painful knot that twisted in his gut as he hung up with his father. That knot had only grown more twisted when Alan called back that night to tell him Charlie was still missing. Don could feel that knot in his gut, formed from the anxiety and worry when two days later, they still couldn't find Charlie.

"Don."

He looked up to see David, standing next to his desk.

Don sat up straighter. "Did you get something?"

David fidgeted. "Not exactly. I called in a favor."

"From…?"

"Do you remember ever hearing me mention Agent Derek Morgan from Quantico?"

Don shrugged.

"He's with the BAU. His team's coming to help look for Charlie."

Don felt the blood drain from his face. The BAU? Was he serious? The BAU didn't help search for lost college professors. "That must have been some favor," he said.

David shrugged. "I only alerted Agent Morgan to the situation. I think Charlie's security clearance caught the attention of the rest of them."

Don nodded. That made sense. His brother's security clearance was higher than his own, higher than most people he knew.

"They'll be here by tonight," David continued. "Maybe they'll find something we can't."

"Like Charlie," Don said quietly.

David hesitated, the placed a hand on his SAC's shoulder. "We're going to find him, Don," he said.

Closing his eyes, Don took a deep breath. He opened his eyes again and looked at David. "We have to find him."