The Gryffindor Common Room, Hogwarts

Harry

Harry tossed unhappily from side to side on his bunk. He couldn't fall asleep. For some reason, knowing that at least some of the Greek myths were true freaked him out even more than the discovery of magic, though he wasn't sure about that. Harry listed severely to the side. Harry looked over. The dark, dim dormitory was outlined by a thin frame of light coming from the doorway. He peered through the small crack of light. Harry couldn't see anything outside.

However, he could hear movement in the common room. Tip-toeing, he silently crept to the door, opening it just a creek, so he could peak outside. His suspicions were true; Percy and some of the others were sneaking out the common room. Quietly, Harry reached for his Invisibility Cloak.

Nico

The journey to the shadow world was longer than Nico anticipated. As he melted into the darkness, he looked around. Ripples of darkness and blackness swirled around him. Nothing could be seen, but they could be heard.

Ghosts gathered at every corner, all begging, pleading, with an unintelligible chatter. Nico pushed past that. Just keep running, just keep running, he breathed deeply. A path of pure darkness was leading him towards his destination. He rounded a corner and appeared at the edges of the River Styx, right under a birch tree. Nico sighed, relieved. At least this is familiar territory, he thought.

Nico peered at the giant, black gates. They seemed to be barely strong enough to withstand a heavy wind, but they trapped eons worth of souls and demons within. Nico reached up, pushing the gates. They creaked slowly, but gradually grew in speed, like a rock rolling down the side of a hill. As he finally managed to open the gates fully, he could sense thousands of cursed souls suddenly alert.

It was no coincidence. What had trapped them for centuries was suddenly opened. However, they'd have to get past Cerberus first, and of course, the River Styx.

Grinning, Nico turned the corner.

Percy

Their group rushed up a flight of stairs, pausing every so often to check for onlookers. The paintings on the walls muttered disapprovingly as they passed. Finally, they reached the abandoned door. Percy put a hand on the knob and tugged. It was ice-cold, and did not budge. "It's still locked," Percy said.

"Hopefully nothing happened to Nico," Will murmured, caressing his hands gently.

"Wait!" Annabeth pointed at the doorknob. Slowly, it turned. The door creaked open, releasing the sound of dozens of spirits. Even without Nico, the group could sense their displeasure about their interruption.

"Quick!" Percy reminded and stepped towards the centerpiece. They looked closer at the altar. Runes were inscribed on all sides, each glowing with a searing, white light. The rune on the center seemed to do the very opposite, sucking in light as if drinking it up, just like Nico's sword.

"Stygian Iron," Jason marveled. Percy glared at him.

"Very helpful," he spat. Jason rolled his eyes.

"How do we get this open?" Annabeth asked, running her fingers along a slight crack. Indeed, what had seemed like a crack in the altar was revealed as a line connecting all the runes together, as if it were a lid to a box.

"Pull!" Percy ordered. They all seized a side of the altar, and pulled as hard as they could. It did not work.

"What do these inscriptions mean?" Jason wondered.

"Do they have something to do with opening the alt-'box'?" Annabeth pondered. They both had the same thoughtful expression that made Percy roll his eyes.

"C'mon! There has to be a clue or something, right?" Percy asked the others.

"You mean like a treasure hunt? Percy-" Calypso questioned.

"There!" Thalia gasped. They all rushed over. Thalia was looking at a faint-looking but very intricate scratch mark on the floor. A lot more scratch marks followed.

"It's some sort of language!" Annabeth cried.

"Six of us remain," Calypso chanted.

"You understand it?" Percy asked, amazed.

"What? It's the old language of magic," Calypso explained, a bit flattered.

"Go on," Thalia beckoned.

"Six of us remain," Calypso repeated. "In the earthly domain. One of us is doomed to fail, aboard the goldenly ship-a-sail."

Percy scrunched up his forehead. "If that is what I think it means then-"

"It probably is," Jason agreed. "I mean... seven? Six of us and one... Isn't that too much of a coincidence?"

"So you're saying... the seven is us?" Piper asked, amazed.

"Well yeah. Six of us are in the 'earthly domain', and one of us died, right?" Jason explained, looking at Leo. "And the ship-"

"The Argo II!" Leo cried. "Wait... so that means... oh. Oh..." Leo pursed his lips. "So which one is me, huh?"

"The scrawny one," Thalia joked.

"Hey!"

Jason cleared his throat. "So... how are we supposed to do this?"

"The altar, maybe?" Annabeth asked.

"So we tell it?" Percy questioned, dubious.

"No, silly. You cast it," Calypso answered, swatting Percy's arm. She began to recite an incantation. The room rumbled, as if in an earthquake. They all looked around, confused. Calypso finished her spell. "There," she declared, satisfied.

"So... what now?" Percy asked.

"Now we wait," Calypso replied. The room stopped shaking. Instead, the tiles with the riddle retracted, revealing a gaping hole.