Dramatis Personae

After a Klingon vessel that had been exploring the other side of the wormhole explodes upon returning, the crew begin acting odd. They become obsessed with a power struggle between Federation and Bajoran factions, and Sisko completely checks out.

It turns out that they have been infected with a psychic virus, forced to play out the destruction of an ancient civilization. This is what caused the destruction of the Klingon ship, and the last (temporarily) surviving member of the crew brought the 'telepathic matrix' with him when he transported aboard.

Eventually, Odo (who is not affected) gets Bashir (who mistakenly believes he is not affected) to create a cure, and they blow the psychic virus out an airlock, somehow.

KRAD and several commenters on the rewatch praise the acting in this episode, despite the weak story. Even if you're entertained by it, I don't think the actors hamming it up is enough to overcome the lack of meaning to the episode. Is there some tension between Kira and Sisko with regards to Bajoran interests? Sure. But nothing that happens here is connected to that, except tangentially. It's forgettable.