Summary: Danny Phantom/NCIS crossover. Jack and Maddie Fenton are asked to install ghost shields on military bases in Virginia and Maryland. While staying on a Marine Corps base, Danny witnesses a bizarre crime. NCIS is called in to investigate and they discover their strangest case yet.

A/N: This story takes place shortly after the Danny Phantom episode "Reality Trip," towards the end of the second season. In the NCIS time-line, it can fit in at any point before Gibbs' coma and subsequent temporary retirement to Mexico.

Murder Most Spectral

Disclaimer: Danny Phantom is the property of Butch Hartman and Nickelodeon. NCIS is the property of Donald P. Bellisario and CBS. This story and all original characters are mine.

Chapter 1: Arrival in Quantico

About a week after Danny destroyed the Reality Gauntlet, life was getting back to what passed for normal in the Fenton household. Only his friends Sam and Tucker and his sister Jazz knew his secret. Knowing that his parents would love him even if they knew he was a half-ghost was comforting. But fighting ghosts was hard enough without those ghosts hurting his parents to get to him.

Danny woke that morning at 3:00, thanks to a visit from the ghost dog Cujo. The green mastiff had decided he wanted to play and dug his way out of the Ghost Zone. By the time the giant dog had gotten tired of playing fetch, it was almost time for Danny to get up, anyway. Needless to say, Danny was exhausted.

Complaining later to Sam and Tucker over lunch at the Nasty Burger, Danny said, "I know he likes to play fetch, but I can't keep it up for 2 or 3 hours every time Cujo gets bored and digs his way into the Real World."

Sam munched on a fry. "Look, Danny, if you don't keep Cujo busy, he'll terrorize the town."

"Besides," Tucker put in, "this is all part of having a pet. You have to play with them, even if they tire you out doing it." He took a large bite of his burger.

Danny glared at the other boy. "You try entertaining a 10 foot high mastiff at three in the morning."

Tucker, thankfully, kept his mouth shut for the rest of the meal. Sam spent that time trying to soothe Danny by reminding him of the damage Cujo caused if left to his own devices. It sort of helped to know that his exhaustion was serving a purpose. At least, until the Box Ghost decided to visit.

All in all, it was a normal day in Amity Park. That was, until he got home for dinner. His parents, Jack and Maddie Fenton, were very excited. Somehow, his mother had restrained his father enough to get him to not blab their news until after dinner. Jazz didn't even know yet, which surprised Danny. Jack's exuberance was not conducive to keeping secrets.

As soon as dinner was over, Danny asked, "So what's the big news?"

Jack opened his mouth, but Maddie put a hand on his arm. "Let me, sweetie." She turned to her children. "We got a phone call from the Pentagon, today. They want us to install anti-ghost security systems in several key military installations. We're heading down to Washington in two days and we'll be gone the rest of the summer."

Jack's dam finally burst. "And you two are coming with us! We'll be staying on base at each place that gets a ghost shield generator, too!

Danny and Jazz looked at each other. A whole summer with their parents, talking about nothing but fighting ghosts? They were doomed.

It was a beautiful day in late July as Danny Fenton walked down the street of the Marine Corps base in Quantico. His parents were busy with the installation of the ghost shield generator. Jazz was reading a book back at the house the base had provided for them. Danny decided to explore the base. How often would he be able to see a military base, after all? He missed Sam and Tucker, but this was a once-in-a-lifetime opportunity.

Today, Danny found himself on the main drag, where all the stores were. The base was a self-contained community, with its own stores and businesses. Danny decided to check out a small local souvenir shop that looked interesting, models of aircraft carriers and battleships decorating the window. The store looked pretty empty, and the owner seemed a little bored with no customers coming in.

Danny entered and began looking the place over. The merchandise wasn't very exciting, most of it looking exactly like what you'd find in any souvenir shop on any major interstate highway. He was behind the first row of shelves when his ghost sense went off, just before Danny heard the door opening. Peeking around the end of the aisle, he saw a man enter the store dressed in fatigues, a billed hat shading his face. The man was completely alone.

The man walked up to the store owner. "Corporal MacLean."

The store owner looked up from the book he was reading. "Retired, Sergeant." Then, he saw the face of the younger man. "Bobby! When did your tour end?"

"Just got back four days ago. I'm so sorry about Evan."

"I know. I wish you could have been here for the funeral." The store owner sighed.

'Poor guy,' Danny thought. 'I wonder where in the world they were at the time.'

The sergeant relaxed his shoulders, more at ease. "So do I. The company held a memorial service the day we sent him home." There was a silence between them for a minute. Then, Bobby got an odd look on his face. "Listen, there's a favor I need from you."

"What is it?"

"I heard about the new security system they're installing."

Danny perked up. Bobby was asking about the ghost shield.

"Yeah. What about it?"

"Some of my buddies in the offices are worried about how this will affect their jobs. You know, how things will be run. They weren't told much."

Danny shook his head. That didn't sound right. As tight as security might be on a military base, Danny was pretty sure they didn't have ghost detail on their duty roster. But Bobby said he didn't know much about it. Still...

"Bobby, the civilians on the base are told even less, and I didn't have the clearance to learn a heck of a lot about base security, even when I was on active duty. Your CO would have access to more information."

"CO didn't tell us much more than what my friends were told. I thought you might still have pull with the officers you served with. Maybe enough to call in a favor for an old friend of your son's."

Danny felt even less at ease. This guy was asking for information he had no right to. The way Vlad might. Danny paid far closer attention to this conversation.

"I don't have that kind of pull. Not enough to get what you want. Maybe enough to find out something before it's released to the public, but not military intelligence." The store owner became suspicious. "Why would you need to know classified information? You moonlighting for the CIA or something?"

"Something." Bobby casually and soundlessly rested a hand on his gun holster. "Mr. MacLean, I need you to help me out here."

"You know you can't circumvent the chain of command. Whatever you're up to must be pretty serious to warrant going over the heads of every officer in your entire company." Bobby said nothing, and the older man suddenly realized something. "You need to go over your officers' heads. Whatever you're doing, you don't want an official paper trail."

Before the store owner could connect all the dots, the Marine pulled his weapon from its holster. Stunned at the store owner's conclusion and the sight of the drawn weapon, Danny's eyes flew wide open. Backing out of sight, he accidentally bumped into a large mug on a shelf next to him. "Oh, crud," he muttered. Both men turned at the sound of ceramic shattering and Danny quickly ducked back into the aisle.

The younger man didn't seem to be aware that they had been overheard, but Danny heard merchandise at the front of the store hitting the floor. Somewhere, in all the noise of many things breaking, there was the sound of what Danny thought was a can hitting the floor. Then, the heavy case the teen was hiding behind slowly toppled over. The merchandise fell off the shelves, hitting Danny before crashing to the floor.

Danny tried to get out of the way, but he tripped on something and fell. The heavy case fell over on top of him, a shelf hitting his head. He tried to get up, but the blow to the head had disoriented him and he gave up. Danny closed his eyes at the bright light reaching him under the case and he knew no more.