It's raining while Arthur is stuck there on the roof, and he moves around in order to get a better view of what's happening inside the Cheese Hall.
The men are hoisting up the captured cheeses into the loft, where they're put in pens. Arthur reenters the hall through a window, and lands in the hay among the cheeses.
He hears Gristle talking about needing to feed the Great One after they zap him, and the men begin to corral the cheeses into a cage anchored to the top of the hall's dome.
Gristle says something about the Great One being ready soon, so long as they can keep up the supply of cheeses and monsters.
That doesn't sound ominous, right?
They load up the cheeses, and the cage they're in descends through a hole. The men leave it there for a few minutes, and then pull the cage back up to the loft. When they do, all that's left inside are a few strings of melted cheese.
The men leave to go have tea.
Arthur is not quite sure what just happened, but he knows it was something bad.