Season 5 of Deep Space Nine begins the Dominion War arc that will dominate the rest of the show. The Federation and its allies face a new enemy in the form of the Cardassian-Dominion alliance, which threatens to conquer the Alpha Quadrant.
Stardate: Unknown. With the war between Klingons and Federation intensifying, Sisko must make a plan to expose Gowron as a changeling. Odo is still having trouble with becoming a solid.
Stardate: 50049.3. The crew is forced to retreat in a crashed Jem'Hadar ship after an attack by the Jem'Hadar. They get the feeling there's something very important about this ship.
Stardate: 4523.7. Darvin, a disgraced Klingon spy, travels back in time to alter some events to his likings. The DS9 crew must find what he's trying to change and prevent it without altering the time line. They'll have to blend in with the crew from Star Trek: The Original Series.
Stardate: Unknown. Sisko, Dax, Odo and Garak find themselves in the past when the Cardassians controlled the station, and a crime that Odo investigated may be the key.
Stardate: Unknown. When Odo and Quark crash land, they must put aside their differences to climb a mountain to signal for help. Jake and Nog try to be roommates, but their different styles clash.
Stardate: Unknown. The discovery of an infant Changeling gives Odo a chance to correct what he sees as the "mistakes" in his upbringing. But as Starfleet's pressure for results grows, he has to turn to his "father," Dr. Mora
Stardate: Unknown. A coded message from the Gamma Quadrant leads Garak to believe his mentor, Enabran Tain, is still alive. He and Worf seek him out, only to discover something much worse: a Dominion invasion fleet poised to attack the Alpha Quadrant.
Stardate: Unknown. Dr. Bashir is selected to be the model for the next-generation of Emergency Medical Hologram (EMH). But he balks when his parents are invited to the station to be interviewed by the EMH programmer, Dr. Zimmerman. There is a dark secret in his family that he's afraid that his parents will reveal.
When a Cardassian official that thinks of Kira as his daughter is dying, he agrees to reveal all he knows to her. But the experience dredges up Kira's memories of her own father's death.
Stardate: Unknown. Dax and Worf accompany Martok on his first command since being held by the Dominion. But the ship they are given hasn't seen victory in months and the crew is near mutinous.
Stardate: 50814.2. The DS9 crew discovers a small colony on a remote world that was originally populated by them 200 years earlier due to a time travel accident with the Defiant. The current colonists' lives depend on making sure that the accident happens again, even though they've now forewarned the crew that it will happen. Each crew member needs to decide if they are willing to give up their lives on DS9 in order to preserve the history of the colony.
Stardate: Unknown. Driven to desperation by the Dominion, the Maquis launch a massive bio-weapons strike towards Cardassia. Sisko must trust the traitor Eddington to try to stop them.
Stardate: 50929.4. Jake and Nog go through hell and high water, from participating in an auction to dealing with the Dominion, to receiving a Willie Mays baseball card to cheer up the war-fatigued Captain Sisko.
Stardate: 50975.2. With the continuing battalions of Jem'Hadar entering the Alpha Quadrant in preparation for war, Sisko decides to mine the wormhole to prevent further troop movement. This provokes a confrontation between the Dominion and the Federation, forcing Sisko to abandon DS9.