“Accession” is episode seventeen of season four of Star Trek: Deep Space Nine.
A Bajoran craft powered by a light sail comes out of the wormhole, yet it never entered the other side. The craft is of a design around two hundred years old. When the sole, Bajoran, occupant is beamed aboard DS9 and questioned, he turns out to be a famous poet from 200 years before. Oddly, he never questions the fact that in the couple of days he thinks he was gone an entire Federation space station has appeared, nor even what the Federation is. The fact that he has been gone for 200 years is quickly brought up, but still, you would have expected some questions before that.
The man also claims to be the Emissary of the Prophets, something that the Bajorans had always considered Sisko to be. Sisko himself – never happy about being a religious icon – is quick to give up the position, but the poet came from a very different Bajor. Before the Cardassians invaded, Bajor had castes called d’jarras, which dictated what a person could do. The new Emissary wants a return to the castes, and Kai Winn apparently agrees. This means that Bajor won’t be able to apply for Federation membership, and other, more serious, problems quickly start coming up.
Keiko is returning to the station after a year away (barring visits) and O’Brien and Dr. Bashir have to get the former’s quarters straightened out from his year of living like a bachelor. Keiko is also pregnant. Worf, having delivered Keiko’s previous baby in the TNG episode “Disaster” makes plans to be a long way from the station so he doesn’t have to do it again.