"They went in through here."
Green found the location that matched the map. The previous group to leave had entered here, heading against the current and into the tunnel.
To be honest, all these openings looked much the same. They had to count them one by one to confirm their positions. To avoid being discovered, the team didn't mark the openings on the Great Hall side.
Only when entering deeper branches did they carve a discreet scratch, agreeing to explore each branch from right to left.
One reason was to guard against the tiny chance of collective amnesia. The other was to prepare for situations like this one, so that anyone following them could tell where they had been and which branch they were in.
Facing the Great Hall, Green backed step by step into the passage, until the dim light diffused by the water mist could no longer be seen. Only the yellow glow of their torches illuminated the surroundings.
The pounding in his chest betrayed how far his composure was from the calm he showed. His swelling veins throbbed against his skull, leaving him in a state of pain and clarity.
His head throbbed as though he had spent an endless night reading by candlelight. Things far more bizarre than the Heterodoxy's accounts in the books had been crammed into his mind, churning and rolling—like shapeless objects spinning to reveal surfaces of impossible dimensions, or an oil-polluted river shifting through a dizzying array of colors.
"We need to move faster," he urged. Then he turned and strode deeper into the passage.
This was pure physical labor, requiring little thought. That left his surplus energy free to run wild, replaying things drawn from what he had seen and heard, yet not limited to those memories.
[Underground, water, moon]
There