During the Romulans' visit to DS9 for a briefing on the developments of the Dominion threat, a high dose of radiation subjects O'Brien to a series of unpredictable temporal displacements, causing him to periodically jump into the near future for short periods of time. While in the future, he witnesses curious events including his own death and worse.
What could've been an exercise in forgettable technobabble (something sister series Voyager has been offering plenty of lately) instead proves to be a fascinating high-concept story and a good outing for O'Brien. Chalk up another punchy direction for Reza Badiyi.
O'Brien's first jump puts him near Quark's bar, approximately five hours in the future, where he witnesses himself talking to Quark about wrecked holosuites. After a brief moment, O'Brien is whisked back into the present. At first, Bashir thinks that O'Brien seeing himself may be some sort of hallucination, but when Dax discovers a quantum singularity orbiting the station at a regular interval, she concludes the residual radiation in O'Brien's body is acting like a "magnet," causing him to be pulled in and out of time. Dax and Bashir begin working on a way to remove the radiation traces from O'Brien's body to prevent any more time shifts.
However, when a subsequent jump turns O'Brien into a witness of his own death—shot by a mysterious phaser-armed booby-trapped device placed behind a panel in some remote corridor of the station—he uses information from the future to avert being killed. Odo opens an investigation to determine why someone would place this device behind the wall panel.
But after saving himself once, another time shift allows O'Brien to see that he dies on the operating table due to undetectable radiation effects. A rather bizarre and intriguing scene has O'Brien talking to a Bashir in the future who gives him information on how he can be saved in the past.
Much to O'Brien's annoyance, Quark labels the engineer a "fortuneteller." The label takes on a whole new meaning when O'Brien jumps forward into the middle of a station evacuation—just in time to see the entire station destroyed.
The sudden way the story drops us right in the middle of this evacuation conveys a confusion and disorder that allows us to experience O'Brien's own bewilderment. One second we're in ops as the crew discusses Odo's investigation. The next second we're in a Runabout with two O'Brien's fleeing the station as it explodes. The sight of DS9 being destroyed is fairly spectacular, if not somewhat disconcerting—some modelmakers put in a great deal of work on a destructible mock-up. The results are quite good. (This is the first time we've seen the station actually destroyed.)
This gives the crew the task of figuring out what will cause the station's destruction and how to prevent it. With Sisko's approval, O'Brien figures a way of injecting himself with a specific amount of the radioactive substance in order to perform a controlled jump forward to just before when the station is to be destroyed.
This is just the beginning as O'Brien jumps forward in time to talk to his future self then witnesses a Romulan Warbird launching a surprise attack on the station. Miles from the past ends up switching places with Miles from the future, because past-Miles is so poisoned with radiation that experiencing another dose of temporal shifting would surely be deadly. Future-Miles instead goes back into the past with the crucial information. This is an interesting twist and a rather brave decision on the writers' part, which gives us some rather paradoxical food for thought. I'm glad they didn't let anything like restraint or plausibility get in the way of fresh storytelling.
In retrospect, the idea that the quantum singularity is really a cloaked Romulan ship makes a lot of sense. The fact is consistent with the establishment of Romulan power supplies given in TNG's "Timescape." That makes "Visionary" a mystery with a genuine audience-supplied clue.
The closing scene, where Sisko confronts the Romulans over their intentions of destroying the station and the wormhole because of their paranoia of Dominion invasion, is a satisfying jewel. I always like it when Sisko sports the no-nonsense attitude.
All in all, this is a great technobabble episode. Technobabble can never really be a story, but when it's used correctly and backed up with real storytelling, an episode like "Visionary" can be born. Sure, the concept is implausible. Sure, O'Brien's time jumps are admittedly way too convenient, placing him in the right place at precisely the right time. But the episode is, after all, called "Visionary."