ST:DS9, Whispers, Episode 214

A well thought-out episode, if there was one. O'Brien spends the entire episode thinking there is some sort of conspiratorial takeover of DS9, related to the upcoming peace talks between the warring factions of another alien race. Characters seem to be hiding things from him, and O'Brien grows more and more suspicious as time goes on.

Turns out, the O'Brien we're following during the show was a clone, and such an accurate clone that O'Brien 2 didn't realize he wasn't the real O'Brien. And as such, O'Brien 2 pulls tons of awesome engineering tricks to break into computer systems, break out of the station, etc. I particularly enjoyed when they tried trapping O'Brien 2 in a force field between two corridor entrances. Rather than try to disable the force fields, he programmed the computer to turn every force field on in the station ("Alright, now come and get me."). They then disabled all of the force fields, letting him pass.

I also liked the bit of misdirection they had. The show was rife with pregnant shots of the "jamaican coffee, double blend, double sweet" O'Brien 2 kept replicating. He even said something to the effect of "You're drinking too much of this stuff, O'Brien." By the end, I was fully expecting something about the coffee he was drinking was keeping him from becoming a pod person.

Because honestly, given the quality of the writing in Star Trek sometimes, that should have been the reveal. I was happy to be proven wrong.