Disclaimer: I don't own Code: Lyoko, and I don't own the Area 51 novels by Robert Doherty, from which I drew a lot of the inspiration for this story. That doesn't make this a crossover, mind you.

Now, on with the show.

Prologue: Burial

It came swinging into the solar system at 3/4 the speed of light, powered by an engine that was far beyond anything humankind had achieved by the year 2006. Closing in on the 3rd planet from the sun, it started to slow down, to observe what was happening on the surface. Earth, at this point, had a single solid landmass, one that, to the scientists of the future, would later be known as Pangea.

"Perfect." One of the beings aboard the spaceship said to its single comrade, in a language that no human, if they had been around, would understand.

The descent into the atmosphere was quick and easy. The ship, which looked roughly like a very large, silver talon, was about the size of a helicopter. A herd of brontosauruses looked up to see it pass by, then, finding it of no interest, went back to their grazing. It landed in a region that would eventually be known as France, and two figures emerged from a hatch in the side.

Arto and Canto were their names. Their species was reminiscent of large, red, upright ants, about human size, with two arms and two legs. They had no mouths visible, but they were able to talk nonetheless.
"Are you sure this is a good planet to hide this thing?" Canto said, looking annoyed, watching the nearby herd of brontosauruses with unease.
"Yes, Canto." Arto said. "It is far, far away from any contact with other systems. There is no intelligent life to speak of. The enemies of the Zethian Empire will never find it here. Come. We have work to do."

Canto went back into the alien craft. A few minutes later, a golden pulse of light was emitted from the tip of the talon, burning into the ground with ease, at a slant. Arto watched the process with ground-piercing detection systems, and indicated to Canto when he should adjust the laser to make the chamber that was to be at the end of the tunnel. He also retrieved a large, flat stone from nearby. When the burning was done, Canto came out of the ship again, this time carrying a wrapped package.

Together, the two went down into the tunnel. When they emerged at the other end, inside the chamber, Canto unwrapped the package. Inside were several different things. One was a compact, cold fusion reactor. One was a tangle of wires and boxes, which Arto quickly set up around the entrance to the chamber and rigged to the reactor. One was a small table. And finally, handling it gingerly, Canto pulled out what looked like an opaque, golden hourglass.

He set this on the table. It was about the size of a man's forearm, with red crystals all along one rim and blue crystals all along the other. There was a slot in the thinnest portion of the hourglass like thing.
"I'd sure like to know why we're hiding this here." Canto said. "If its as powerful as they say, then why don't we use it to win the war?"
"There is only one, and no more can be made. It cannot be everywhere at once. The war is far beyond the point at which it can be won, even with this thing'shelp. We hide it so that they the enemies of the empire will not get their hands on it when the empire falls."
"Yes." Canto mused. "I see now. That would be a disaster."

Canto looked at it with wonder. The object was a grail, a type of cup. But to those who knew it's secret, it wasn't just any grail. It was The Grail, to their species at least. Not the holyone popularized in Earthly myths and legends, but something with a far, far different origin.

Canto then pulled out what looked like a small pen. He aimed it at the back wall, turned it on and started carving out the letters of their language on the back wall with the laser that was emitted.
"What are you doing?" Arto asked.
"Writing a warning."
"I told you. There is no intelligent life on this planet. And even if there was, they wouldn't understand our language."
"Maybe... but I get the feeling that there may be some someday. They could decode it."
"Moron."
"Oh, be quiet. Rig the security device, and lets get out of here. We still need to bury the key."

Canto reached out and pulled one more thing out of the package. It was a sword, made of a light but very strong metal from their home world. It fit perfectly into the slot in the Grail, and was the only way its power could be used. He put it back into the bag, and the two aliens walked out, after Arto turned on the security device and made sure it was powered. The power source would last for a long time; hopefully long enough that the enemy forces would be repelled if they did find it, which was unlikely.

The last thing they did was slide the flat stone into place, so that it covered the entrance to the chamber just a little way into the sloping tunnel. It was placed horizontally, like a trap door, rather than vertically. Canto carved the words "DANGER" and "DO NOT ENTER" on the stone, then they made the long trek up to the surface through the tunnel.

They got into their ship and took off, first to go to what would become the Nevada Desert, where they buried the Sword, then out into space, heading home. Within twenty years, the war would be over, and their kind would go extinct at the hands of their enemies. But the Grail, and the horrible and wonderful powers it contained, were safe.

Years stretched into centuries, and centuries into millennia. Pangea broke up, the dinosaurs went extinct, and much of the land over the hidden chamber was eventually eroded, eating away the long tunnel. By the time an intelligent species evolved on the face of the planet, the chamber was no more than a few feet below the surface, but was miraculously undisturbed despite the rise of civilization in France, and the eventual building of a city in the region, a large abandoned factory occupying the place where the brontosaurus herds had once grazed.

That is, until Yumi Ishiyama and her mom decided to make a garden in one corner of their backyard. Yumi uncovered the stone blocking the entrance in the first five shovelfulls of dirt.