the story: O'Brien keeps jumping into the future, where things are spiraling wildly out of control for the whole station.
what it's all about: "Visionary" is an episode that is so fun it almost doesn't matter that it could have happened in any series, which is usually a knock against Deep Space Nine trying stuff like that, but here is anything but.
The crux of it is the classic template of let's-torture-O'Brien!, a reliable source of material if there ever was one. Let's just get that out of the way. If anyone can sell material like this, it's O'Brien, who gets to enjoy yet another scenario that's so entirely bonkers only science fiction can get away with it. By the time he starts putting two and two together, seeing his own future self, replacing himself, the fun just explains itself.
The rest of it is vaguely centered on series elements, like the Romulans complaining about Starfleet not living up to its end of the bargain (I may not have previously mentioned that the station's new warship, the Defiant, comes equipped with a cloaking device on loan from them), but it's really just an excuse to let loose all manner of mayhem, including more Klingons than you can shake a stick at (although the Romulans certainly try). This was before the Klingons were really an intrinsic part of the series, so it does come off as fairly random to involve them here.
But don't worry about such things! Just run with it! Because it's a pretty fun episode, and that's all you really need to know.
- franchise - Stands proudly in the tradition of fun sci-fi storytelling in Star Trek.
series- Inessential to Deep Space Nine, however.
- character - Although it's prime O'Brien material.
essential- Keep calm and just watch it already.