On the whiteboard, a pentagon had begun to hum . Its lines thickened, turned silver, then opened —like a door folding inward on an impossible hinge.
“You’ve broken the consistency!” Mr. Eldridge shouted, arriving just in time.
A boy named Leo, usually half-asleep, gasped. “Sir… the board.”
Mr. Eldridge understood. He stepped into the center of the collapsing Hub and drew the simplest thing he knew: a straight line between two points.
Mr. Eldridge stepped through. The others followed.
The Hub shuddered.
“Trace the edges in the air,” he said. “Visualize each face. Now—rotate it.”
“Holy… Pythagorean theorem,” whispered Maria.