Apocalypse Rising, DS9 5
Gowron is a Changeling! NO – Martok is a Changeling! And Worf, Sisko, Odo and O’Brien must disguise as Klingons to expose him. (By hitching a ride with renegade Dukat and his killy-mobile!)
To see the gang take Klingon lessons is a hoot. To watch them tell tales and drink bloodwine is fun, too. And it looks like the Federation-Klingon disagreement is at and end.