AUTHIR'S NOTE: Here's the sequel to Return of the Hero for those of you who never read it on my dA page. It takes place five years after Danny needed to leave, and it introduces a few new characters that you will see in the following adventures.

For the first half of the story, Sam and Tucker, as well as the newest member to the Phantom Crew, Andy Fenton, are the protagonists. Feel lucky that I'm publishing this story in chunks on ; those who read it on deviantart nearly dropped dead with every cliff hanger I left. Haha!

Anywho, without further ado, here is Danny Phantom: Mystery of the Spirit Gems!

Morning was just dawning over the city of Houston, USA, but the people working at NASA's Johnson Space Center had been up hours before the sun. Astronauts, doctors of science and military soldiers walked the grounds, getting ready for the return of another shuttle, even though the shuttle was returning in Florida, thousands of miles away.

It was no different in the laboratory of British-American space researcher, Dr. Michael Johnson. He loved the feeling of getting up early in the morning and working on samples brought back from the moon and other areas in space by the space rovers and astronauts. Everything from the unknown fascinated him. Deciphering riddles and puzzles were some of his favourite hobbies.

And thanks to a certain Space Cadet-turned astronaut who had entered the space program several years earlier, Johnson was also fascinated by the theory of ghosts existing.

Michael Johnson was one of the Space Center's most respected scientists; even the students who enrolled every two years looked at him as a model and asked him plenty of questions. People always came to his sermons and lectures, knowing that they would learn something new. They had even given him the name of Space Father, no thanks to the fact that he shared the same last name as the man the Space Center was named after.

Johnson was studying another microbug under his electronic microscope when the door to his laboratory opened. In stepped Lieutenant Jones, the center's director and veteran marine and astronaut.

Johnson looked up from his work and removed his goggles. "Oh, Lieutenant Jones, what a pleasant surprise, Sir," he greeted with his welcoming grin and British accent. "You're here mighty early, today."

"Have to, considerin' the shuttle's comin' down this mornin'," the Texas man replied, walking over. "If it wasn't, I'd still be in bed, but you know them workers nowadays; like to slack off in the mornin' if they ain't had their coffee."

The scientist laughed softly as his superior and old friend walked up to his desk. The built, wide shouldered director looked over the man's work. "Still workin' on that thesis of yours, Professor?" he asked, crossing his arms.

Johnson sat at his desk. "As a matter of fact, I am, Lieutenant," he replied, gathering his papers. "And I'm almost near completion."

"Good! Your work is half of the fun here at NASA."

"You're flattering, Sir."

"I try not to. Say, how's that portal of yers workin'?"

Johnson raised his head and looked at the giant steel ring that was bolted to the wall nearby. "Oh, that old thing?" he said. With a sigh, he turned his head away while playing with his thick, gray moustache. "Haven't tried it out for several years."

"But it still works, right?" Jones said, catching the man's attention. The director looked at the professor's desk. "You designed it with the help of one of our former students, no?"

"Yes, yes, but I haven't had the heart to use it since he-!"

"Hey!" Jones leaned over and grabbed a picture frame sitting on Johnson's desktop and held it up. He grinned and pointed at the photo. "This is the kid, right? The one with the Ghost Hunters as parents?"

Johnson took the photo frame and smiled. It contained the ID photo of his most apt student, the one who had helped him perfect his portal. The young man had jet black hair that flipped forward and bright blue eyes. Although young, his eyes contained wisdom no one had ever known.

"He's that kid from Amity Park, right?" Jones added. "That uh, Fenton kid…"

Johnson laughed softly before nodding. "Danny Fenton," he said softly.

"Yeah, I remember him now! The one who suggested startin' the Special Missions!" the Lieutenant added with a grin. "In all my years of workin' here at NASA, I ain't never seen such a determined man. Daniel sure as heck wanted in on the whole Space Program thing, didn't he?"

"He certainly did. Studied longer than anyone else I knew."

"It's a miracle we even chose him. He didn't do too good in high school, did he?"

"Nope; a D average student."

Jones chuckled softly before grabbing another photo frame. "I spoke to one of his Scouts leaders back when I was checkin' his references," he said. "The man said that Fenton had more spunk than most. He was incredibly shy and clumsy, but boy did he work well when he wanted to get the job done! If we didn't choose him for his grades, we chose him for his spirit. He had way too much of it, and all those theories about improving on the shuttles? And how to gather more information? He was a genius, Johnson; a real genius. And real geniuses don't do good in high school!"

"Is that why he wasn't needed to have three years experience?" Johnson said with a chuckle taking the other photo frame. This one contained a picture of both him and Danny when they were working on the portal.

"I think so. Apparently, according to his sister, Jasmine, Daniel was already familiar with how the controls in a shuttle worked. When we tested him out in a simulation ride, he took the entire staff by storm on how well he could handle a situation. Amazing, Johnson; it was as though he had known how to do this stuff for years. I wonder how he learned how to fly so well?"

Johnson smiled secretly and put the frame down. "He had his reasons," he said under his breath.

Both men were silent before Jones spoke up again. He looked at the professor with gentle, dark brown eyes. "Did you… ever find out what happened to him?" he asked softly.

Johnson sighed and looked at the photo of Danny. "No," he said heavily. "According to his parents, he's still missing. They've been searching for him everywhere. They have proof he's still alive, but they don't know where he could be."

"Cheese Nibblets; how long's it been since that summer already?"

"About five years, Sir."

Jones passed a hand over his face and shook his head. "Dang," he whispered. "That's such a shame, really. Daniel had such potential. He was such a good student. Despite his shyness and his solitude, he knew how to work in a group, and even lead it. He was such a smart kid. Would have made a great Captain for those Special Missions he wanted to start." He stood up straight. "You did tell his folks that, if he ever did show up again, he still had a position here, right?"

"I did, Sir."

"Good. Because it's not every day that we get good Astronauts like him. He'll make a great team leader."

Johnson smiled weakly and stared at the portal across the room.

Jones remained silent until finally sighing loudly and turning around. "Well, I'd best be off to the deck, then," he said. "Before they bring in the shuttle without me." He stomped a foot and saluted the doctor professionally. "Dr. Johnson," he said.

Johnson pushed up his glasses and nodded politely. "Lieutenant," he answered. Saluting the way the military did had never been something he was comfortable in doing.

Jones bowed respectfully and walked out of the lab.

Johnson watched him leave before looking at the photo frame of his favourite student. "I know you're not missing, Danny," he whispered. "But where on Earth would you be?"

He waited a moment before putting his things aside and opening a drawer. Inside sat a small box. He pulled out the box and set it down on the desk. He unlocked it with the aid of the key around his neck and carefully opened it.

Inside sat a red crystal that was shaped like a square. It glistened in the light as a halo of light pulsed around it.

Johnson smiled and held it up. "Do you remember when you found this for me?" he said softly. "I had asked you to bring back some samples, and you brought me this back. Isn't it beautiful?"

All of a sudden, the gem began to vibrate and broke free from the man's grasp. Johnson gasped softly and pushed his chair back as the gem fell onto the floor. Then, it slid beneath his desk and flew up to the portal against the wall.

Johnson stood up and stared at it. The gem seemed to want to enter the portal.

"What in the world?" he said in awe, walking around his desk and strolling up to the portal rim. He picked up the gem, studied it for a moment before suddenly noticing that, on the side of his portal, there were three engravings. The first was smooth and oval shaped; the second resembled the jewel in Johnson's hand; and the third was triangular.

The scientist stared curiously at his gem and then placed it into the slot that it seemed to fit in. It fell into it with a soft click!

The portal suddenly hummed and jerked. Johnson gasped and jumped out of the way as the doors over it slid open. There was a bright flash, and then the green swirl of light appeared, forming the portal door that led to the dimension on the other side.

The Ghost Zone.

"Why would that gem activate the portal?" Johnson wondered aloud, rubbing his chin.

The computer beside the door suddenly began to beep, catching his attention. "Location received. Location received ," the computer announced unemotionally.

"Location?" Johnson echoed as numbers appeared on the screen. "Location of what?"

The data finished typing out and began to blink and beep. Once it had finished, a digital image of a figure was constructed beside it.

Johnson watched silently as it was generated and gasped in shock when the diagram had finished. It was the image of a ghost, with snow white hair and green eyes, dressed in a black suit with white gloves and boots. After a moment, a white line passed over the diagram and replaced it with the image of a young man with jet black hair and blue eyes, wearing the everyday clothes of an American.

Johnson covered his mouth before speaking again. "Daniel?" he whispered.