DS9 Season 5 Summary . Sisko , Odo , O ' Brien , and Worf are sent on a mission to expose Chancellor Gowron as a Changeling infiltrator , only to discover that it was Martok who had been replaced . The Changeling impersonating Martok is killed , but Gowron is still not ready to end the war with the Federation . The crew is able to capture a crashed Jem ' Hadar ship and return it to Starfleet . Worf helps Quark woo his ex - wife Grilka , while he and Jadzia Dax start a relationship initiated by Dax . Jake Sisko is doing a report on Julian Bashir in a later episode when they are called to help a Federation colony against Klingon attack . Jake has his first real dealings with death and the horrors of war . Keiko O ' Brien later gets possessed by a strange noncorporeal being who forces Miles to do whatever she says or else she ' ll kill Keiko . Miles is , of course , able to outwit the entity , which turns out to be a pah - wraith , who was attempting to kill the Prophet s . The crew travels back in time to the 23rd century and thwarts a plot by Arne Darvin to kill James T . Kirk , ( unwittingly reintroducing the previously - extinct tribble species to the galaxy in the process ) . Odo is forced to reveal that he had three innocent Bajoran s executed during the occupation . Later , he and Quark crash on an L - class planet and must climb a mountain in order to get a signal through to Deep Space 9 . After an accident in the holosuite , Sisko begins having visions of past , present and future , preventing Bajor from joining the United Federation of Planets by claiming that it will be disastrous for Bajor to do so . A few weeks before giving birth to Kirayoshi O ' Brien , Kira Nerys tracks down a Cardassian who has been killing members of the Shakaar resistance cell as revenge for having been disfigured by one of their attacks . Odo receives a sick infant Changeling from Quark which he attempts to nurse back to health , but with no success . However , before it " dies " it absorbs itself into Odo ' s body and gives Odo back his shape - shifting abilities . Sisko vows to track down and arrest Maquis renegade Michael Eddington after he attacks a Federation starship . Sisko poison s a Maquis colony and Eddington agrees to surrender . Garak receives a signal from Enabran Tain , indicating that he is alive in a Dominion prison . He and Worf attempt a rescue , but are captured themselves , where they discover the real Martok and Julian Bashir , who has also been captured and replaced by a shapeshifter . Tain acknowledges Garak as his son before he dies . The rest escape and return to the station . An attempt to seal the wormhole to prevent the impending arrival of a Dominion fleet is unsuccessful , thanks to an act of sabotage by Bashir ' s Changeling replacement , who is later killed during a failed attempt to destroy the Bajoran system by triggering a supernova within the Bajoran sun . Dukat reveals that he has negotiated Cardassia ' s entry into the Dominion , becoming absolute ruler of his planet under Dominion rule . In response to the sudden change of fortune in the Klingon ' s war against the Cardassians , Gowron agrees to Sisko ' s proposal to reinstate the Khitomer Accords , restoring the alliance between the Federation and the Klingon Empire . General Martok stays on DS9 as Klingon representative for the new alliance . Julian Bashir meets the creator of the EMH , who wants to use Bashir for his next Emergency Medical Holographic program . It is discovered that Bashir had been genetically altered to make him stronger and smarter as he was " slow " as a child . Odo falls in and out of love with a mysterious woman , Quark begins smuggling weapons " illegally , " but has a change of heart . Tekeny Ghemor returns to the station and reveals all his secrets to Kira before he dies . Dukat and Weyoun try to prevent it , but are too late . Quark finds out his mother and the Grand Nagus had fallen in love , and Worf accompanies Martok on a mission to rescue another Klingon ship from the Jem ' Hadar . In return , Martok lets Worf into his House . The crew discovers an alternate timeline by the crew aboard the which has the " Defiant " being thrown back in time and crashing on a planet , and a world of eight thousand being created by the survivors of this crash . This event , however , is prevented by an alternate version of Odo , who confesses his love to Kira . After the Cardassian - Dominion alliance has nearly wiped out the Maquis , Eddington tricks Sisko into releasing him so they can prevent a last strike . He dies in a blaze of glory , allowing the survivors to escape from the Jem ' Hadar . O ' Brien , Garak , and Nog travel to Empok Nor to salvage station parts , but Garak is infected by a Cardassian virus and turns to a murderous rage . Jake and Nog manage to cheer Ben Sisko up by offering him a baseball card . The Dominion offers Bajor a non - aggression pact , which they resist at first , but Sisko endorses it so they will stay out of the fighting . After the crew decides to mine the wormhole to prevent further Dominion reinforcements from coming through , the Dominion attacks and the crew – including Garak – is forced to abandon the station , escaping on the " Defiant " . Odo , Kira , Quark and Jake stay behind as Dukat , Weyoun , and the Jem ' Hadar occupy the station . The Dominion War has begun . . .