Returning from a Bajoran conference on the Cardassian Occupation, Sisko, Odo, Dax, and Garak pass through a plasma storm and are rendered unconscious. When they awaken, they are on Terok Nor seven years ago when Odo was the security chief. Trouble is, the chief on the station is not Odo. Instead, it is Odo's predecessor and the four DS9 crew are Bajorans.
When the Cardassian occupation of Bajor ended in 2369, the mining space station Terok Nor was left abandoned, its systems ripped out. By invitation of the Bajoran provisional government, Starfleet stepped in to oversee the rebuilding and day-to-day operations of the newly christened Deep Space Nine.
The years of Starfleet's nonintervention into Cardassian matters, however, had taken its toll on relations with the Bajorans. Consequently, Starfleet's position was a tenuous one; many Bajorans, suspicious and hostile as a result of decades of Cardassian oppression and brutality, did not greet the Federation's presence with open arms. The Federation's assistance is put to the test as DS9 becomes a center of travel and commerce that stretches into the Gamma Quadrant.