Spinner is a episode in Season 4.
It all starts one day when Phineas wants to build a carnival.
He includes a spinning thing.
Phineas and Ferb blast into this old abandoned mansion and have to get out
On the first floor Phineas and Ferb have to build a weird device.
Phineas: Hmm... What's this machine.
Isabella: Maybe it has to do with sound.
Phineas: It has a handle on the top.
Isabella: But where's the handle.
Baljeet: Maybe it's in those rooms.
Gretchen: We must be careful though.
Perry jumps down through floor hole in floor falls into monogram's HQ.
MM: Your mission today
MM: - is to stop
MM: Sorry, we're breaking up.
TV goes blank.
Just a link to Spinner ch 2