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 provisional Bajoran government, Starfleet stepped in to oversee the rebuilding and day-to-day operations of the newly christened Deep Space Nine. DS9 soon became a center of travel and commerce thanks to a newly found stable wormhole leading to the largely unexplored Gamma Quadrant.
Sisko becomes uncomfortable when the Klingons station a task force to help defend against the Dominion. Worf is summoned to find out their true intentions.
The Klingons attack Cardassia in an attempt to overthrow the planet's newly installed civilian government. When the crew of Deep Space Nine saves the members of the new government, they fall under attack from the Klingons as well. Worf is transferred to Deep Space Nine.
An elderly Jake Sisko relates the story of how he lost his father to a temporal displacement accident.
Bashir assists a rogue group of Jem'Hadar attempting to overcome their addiction to Ketracel White.
Kira and Dukat embark on a mission to find lost Bajoran prisoners. On the mission, Dukat reveals that he too has someone he is concerned about on the ship, a Bajoran woman with whom he had an affair.
Dax is reunited with one of her former hosts' mates, and the two struggle with their feelings for one another.
The USS Defiant becomes trapped in a planet's volatile atmosphere after battling with the Jem'Hadar.
Quark, Rom and Nog are accidentally thrust back in time to Roswell, New Mexico, Earth in 1947.
Worf, Dax and a revered Klingon warrior, Kor, search for the Sword of Kahless to unite the Klingon Empire.
Bashir plays a 1960s secret agent in a holosuite, but when it is used in an emergency to store the transporter patterns of some of the crew, he must make life or death decisions.
Sisko and Odo are brought to Earth when it's suspected Changelings are infiltrating Starfleet.
As Sisko and Odo prepare for a Dominion invasion they discover a plot to place the Federation under military control.
Odo's hidden feelings for Kira surface when the visiting Bajoran First Minister begins to court her.
Dukat seeks Kira's help in regaining his rank in the Cardassian Empire.
Cast out of Klingon society because of Worf's dishonor, his outcast brother asks Worf to kill him.
Rom creates a union for Quark's employees and goes on strike.
A famous Bajoran poet who disappeared over 200 years ago appears from the wormhole and convinces Sisko that he is the true Emissary.
Worf accidentally destroys a civilian ship during battle and faces a hearing to determine whether he should be extradited to the Klingon Empire.
O'Brien is incarcerated for 20 years on an alien world on charges of espionage. However the experience was implanted into his mind, and O'Brien struggles to re-adjust to station life.
When the Mirror Universe counterpart of Sisko's deceased wife lures Jake to the other side, Sisko must follow and help the human resistance against the Alliance's forces.
While Odo assists a pregnant Lwaxana Troi, Jake falls under the spell of a mysterious woman.
Sisko learns that his girlfriend Kasidy may be a Maquis smuggler.
Sisko and the Defiant crew join forces with the Jem'Hadar to stop a group of Jem'Hadar renegades from gaining power.
Bashir tries to free the population of a Gamma Quadrant world of an engineered disease left by the Dominion 200 years ago.
Quark is diagnosed with a terminal disease and sells his body parts on the Ferengi Futures Exchange.