You step in beside Snape, keeping your wand trained on the book as the chamber quakes around you. Together you pour magic into the countercharm, your spell threading through his with a sharp, reluctant precision. The blue flames snap upright, then dim as the open book lashes its pages like wings in a storm. Beneath the stone, the pressure that has been climbing for minutes finally hesitates, as if the castle itself has drawn one cautious breath.

Snape grits out the last words of the reversal, and the chalk symbols around the circle crack like thin ice. A harsh pulse rolls through the hidden room, then another, each one weaker than the last, until the trapdoor settles with a heavy, final thud. Dust drifts down in a soft gray curtain, and the eerie whispering from below fades into silence. For the first time since you entered, the chamber feels still, though the danger in it has not vanished so much as retreated.