Joy decided the living-room carpet needed vacuuming, what with the shredded cardboard, scattered kitty litter, and other kitten-related detritus.
So, into the cage with the Muons, and out with the vacuum cleaner.
The beast being switched on, the kittens' manner went, in the span of a couple of seconds, from curious to alert to alarmed to ZOMG PANIC CLIMB THE WALLS!
The noise having been interrupted and the little furballs having been extricated from the high corners of their cage, I took them back to the bedroom until the monster had completed its work and ceased its howling.
After which... I carried them back out to the living room; Top Hat, being placed on the floor, promptly scampered off to the old favorite sanctuary under the dining table. Huckleberry, who had been riding on my left shoulder, hopped down and followed. Southmoon migrated from my right shoulder to the middle of my back and just wanted to stay right there, even when Huckleberry came looking. Eventually, though, I coaxed her off - I couldn't exactly lie there all day - and she joined the crowd under the table, venturing back out a few minutes later when I was in the kitchen.
They seem to be a bit worried about the living room not being a safe playground anymore.
Oh, well: I assume they'll adapt. Sooner or later, they'll presumably all end up in homes where cleaning is a regular occurrence.
Update: they stayed under the table for a couple of hours, and when they ventured out they were very subdued, and cautious about setting foot on the carpet. They're perking up now, though, and starting to play again, including the occasional attempt to play with Piggy's tail.