The heat exchanger began to scream while Iven was still halfway down the ladder.
The sound came up through the iron cage beneath him: a high, grinding note with a heavier knock underneath it. Hot vapor poured between the floor plates. On the platform above, Mara Doss had one hand around the ladder rail and the other clamped to a speaking tube.
“Intake closed,” she shouted into it. “Not the return. If you close the return, the lower shift loses its air.”
The answer came back as a blur of words and metal hiss. Mara listened, swore, and pointed toward the red wheel on the far side of the exchanger room.
“Second intake is still open. Someone up there doesn’t believe the first one failed.”
“Do they believe the screaming?” Iven called.
“They think it’s a bearing.”
“It is a bearing.”
