The Assignment ( episode ) After returning from the Fire Caves on Bajor , Keiko ' s body is controlled by an alien lifeform that forces her husband O ' Brien to do its bidding or else face the death of his wife . Summary . Teaser . In Quark ' s , the day has started and Quark is busy . Rom enters , just off the night shift . Quark makes him his usual , puree of beetle , but Rom says today he ' d rather try bacon and eggs with corned beef hash , a favorite of O ' Brien ' s . Quark disapproves of the Human choice of dinner but begrudgingly makes it . As he normally does , he further questions Rom ' s choice of job , but Rom likes his job , despite being assigned to the graveyard shift fixing the waste extraction system . Meanwhile , Miles O ' Brien has discovered that Julian Bashir has accidentally killed Keiko ' s Idran hybrid bonsai tree s that O ' Brien was caring for while she was away visiting the Fire Caves on Bajor for the last five days . Bashir had dropped by the O ' Brien ' s quarters and saw that the plants were dry , so he water ed them . Unfortunately , too much water rots the roots . Upon spotting the ruined trees , Miles and Keiko ' s daughter Molly informs her father that " " Mommy ' s going to be mad . " " Later , he welcomes Keiko home and begins apologizing . However , as soon as she gets off the transport , Keiko informs Miles that she ' s not Keiko , but someone who has taken over her body . Whoever is inhabiting Keiko threatens Miles with his beloved wife ' s life and the life of their innocent daughter Molly claiming that they ' ll kill them both if he doesn ' t do exactly what she wants . O ' Brien at first thinks that his wife is trying to play a joke on him , but is quickly persuaded otherwise when the entity causes her to choke . It stops choking Keiko just as easily to warn O ' Brien off from calling the infirmary . Act One . Miles is ordered to reconfigure certain parts of the space station but is not told to what end . The alien convinces him that she can use Keiko ' s knowledge to know that Miles has already come up with a plan and will try to talk to the crew , however , it also assures him it will kill Keiko instantly , even if those plans have some success . They go back to their quarters , and Miles gets some more details . The alien is also determined to keep up appearances with their friends , answering the door when Bashir comes in , and promising to hold a birthday celebration for Miles , as Keiko had planned earlier before leaving for Bajor . Soon , Rom is excited about being called to a meeting on the " swing - shift " to replace Duarte , an ill worker . He tries to fit in by asking what they drink on the shift , and asking where the ill worker normally sits , but the other workers treat him coldly . Unphased , he gets a raktajino . Just then , O ' Brien appears on the monitor and assigns the engineers their jobs for the day , a change of plans . He gives a short description of what he ' s doing , and says he ' ll be working alone , asking them not to bother him unless its absolutely necessary . As O ' Brien works , he has the computer scan Keiko to confirm her identity , which it does . He then asks the computer how long it would take to knock out Keiko through various means ; however , all would take too long as the entity only needs a fraction of a second to kill her . " " God help me , " " O ' Brien says as he then gets to work . Act Two . During Miles ' birthday celebrations , the inhabitant draws on Keiko ' s brain to act like Keiko , and no one other than Miles knows any different . Captain Sisko is especially impressed by the Q ' parol that she served , showing that the alien has access to all of Keiko ' s memories and talents . Jake Sisko asks Keiko if she saw any Pah - wraith s in the Fire Caves , prompted by Odo ' s sharing of Bajoran legends . The inhabited Keiko teases Odo for believing in " the wraiths , " which Odo denies . O ' Brien has trouble keeping pleasant , and finally breaks his glass when he sees the alien with Molly . With everyone else disturbed , he leaves to the other room and the alien follows . O ' Brien insists he ' s done everything it wanted , but the alien admits that was just a test – the real work is to come . That night , Miles insists the alien tell him what to get done , but the alien is making the rules . It refuses and makes O ' Brien sleep in the bed , for fear Molly will have a nightmare and come in . In the morning , the alien hands him a PADD with his instructions . Miles finally decides to warn Sisko about what is happening , but , before he can get to Sisko , he hears Keiko call out his name and watches in horror as the inhabitant forces Keiko to throw herself over the railing on the upper level of the Promenade . Act Three . Dr . Bashir treats her injuries in the infirmary while Sisko and Odo question O ' Brien about the incident and about why he was on the Promenade . O ' Brien evades the questions and insists to Bashir that he visit Keiko at her bed . The evil inhabitant gives Miles an ultimatum : complete the reconfigurations in thirteen hours or it ' ll kill Keiko and Molly . O ' Brien agrees , and leaves , starting a countdown clock to stay aware of the deadline . The Pah - wraith asks O ' Brien to give it a kiss , which he reluctantly does while Bashir stands nearby . As he starts to get to work later , Rom comes to the chief , having finished his work already . Miles is very impressed that Rom got his workload done so fast and gets an idea . He decides to enlist his help to get the modifications done , claiming its a secret assignment that Sisko and the senior staff know all about ( while also warning him not to mention it to them ) . With the help of Rom , Miles manages to complete most of the work , however , as he is working in Ops in the early morning , Commander Dax pulls him away , having discovered anomalies in the station ' s systems . She shows what she ' s seen to him , and , he brushes it off as minor deviations , but Dax suspects sabotage and intends to alert security and wakes Sisko . Act Four . Sisko calls a meeting of O ' Brien , Odo , and Dax to discuss the sabotage . They eliminate other factors , and lead to one of the maintenance crew . Desperate to throw the officers off his scent and needing a distraction , O ' Brien leads Odo to Rom , still working in a junction . Odo takes him to a holding cell , and O ' Brien shares a knowing glance with him as he goes . Miles stays to survey the " damage " and then continues it . During the interrogation , Rom refuses to tell Odo anything ( even his name ) , instead calling for O ' Brien . Odo calls him to the security office , and , pressed for time , O ' Brien is forced to override security measures for the holding cell Rom is in , so that no one can listen in . He also has the computer reconfigure gravitic sensors , intending to be back within ten minutes . O ' Brien goes to see Rom , who is concerned about the intensity of the interrogation , but also assures O ' Brien he will stick to their " mission . " However , Rom then asks why O ' Brien ' s modifications are converting the station into a gigantic chroniton emitter . O ' Brien is surprised he guessed it . Rom believes the intent is to kill the wormhole alien s , and asks why they are doing that . O ' Brien is stunned . Act Five . O ' Brien hadn ' t realized the effect of the chronitons on the wormhole aliens , having been so on edge . He wonders aloud about this , making a connection between the wormhole aliens and the Pah - wraiths . Rom , having been educated in Bajoran myths by Leeta , explains that according to the Koss ' moran , the Pah - wraiths were cast out of the Celestial Temple by the Prophets . O ' Brien now knows that Keiko ' s intruder can only be a Pah - wraith from the Fire Caves , and is planning to use a chroniton beam to kill the Prophets . O ' Brien asks Rom to play dumb for awhile and rushes out . He gets back to work on the junction , with a newfound purpose , however , the newly - solid Odo confronts him . He knows that O ' Brien was behind the modifications , so O ' Brien knocks him out . He finishes the station modifications , and takes the Keiko / Pah - wraith to a runabout , coldly telling it that he figured out its plan but doesn ' t care about the Prophet / Pah - wraith conflict : he only wants his wife back . Once in position near the wormhole , O ' Brien activates the emitters on the station , but targets the runabout instead of the wormhole , killing the deranged Pah - wraith inhabiting Keiko once and for all . Keiko and Miles embrace . When they return , Sisko asks Miles for an explanation . Back in their quarters , Keiko reveals that she knew what the Pah - wraiths were doing , but could not intervene . Keiko tells Miles that she doubts the Pah - wraiths would have spared them . The next day , a tired but excited Rom enters Quark ' s . Quark warns him that the night shift is obviously too much for him but Rom explains that he wasn ' t working , rather he was out celebrating his now permanent promotion to the day shift ; his reward for helping O ' Brien . Quark sighs as Rom then proceeds to order pancake s , sausage s , and pineapple : the breakfast of the day shift . Memorable quotes . " " Is there something wrong , chief ? I can work slower if you want me to . " " " " Culpable deniability . I understand . Don ' t worry about me , chief . My lips are sealed . Nobody will get anything out of me . Not even my name . " " " " Rom , everybody on the station knows your name . " " ( confused ) " " Right . " " ( a pause ) " " But I won ' t confirm it . " " " " Everyone has enemies . Even the Prophets . " " " " That ' s right . They ' re not just wormhole aliens ; they ' re Prophets . Part of Bajoran mythology , just like the Pah - wraiths of the Fire Caves . So what have those wraiths have to do with the wormhole aliens ? " " " " Kosst Amojan . " " " " What ? " " " " It ' s a Bajoran legend . From the verb Kosst , meaning " to be " , and Amojan , " banished " . Leeta ' s been telling me all about Bajoran legends . She can go on for hours . She says I ' m a good listener . " " " " According to Leeta , the Pah - wraiths used to live in the wormhole . They were part of the Celestial Temple . " " " " They were Prophets ? ! " " " " False Prophets . They were cast out of the Temple , exiled to the caves where they were imprisoned in crystal fire cages and forbidden to ever return lest they face the wrath of the true Prophets . " " " " So if these false Prophets were to return to the Celestial Temple . . . " " " " I don ' t think they ' d be welcomed . " " " " For the first forty minutes it was like pulling teeth even getting him to admit his name . " " " " Well , Rom , I ' m glad things are going so well for you . " " " " No you ' re not . But thanks , anyway , brother . " " Links and references . References . anesthetine gas ; bacon ; Bajor ; Bajoran ; Bajoran language ; Bajoran mythology ; Bajoran spiny basil ; Bajoran wormhole ; birthday ; birthday cake ; blood vessel ; bonsai tree ; brain ; brain hemorrhage ; butter ; Cardassian s ; Cardassian vole ; cascade feeder ; Celestial Temple ; " Chief ' s Special " ; chocolate ; chroniton beam ; coffee ; comm link ; corned beef hash ; crystal fire cage ; dabo girl ; Dahkur Province ; Davis family ; day shift ; deflector grid ; Delavian chocolate ; dermal regenerator ; Duarte ; egg s ; emotion ; exile ; eyebrow ; fashion ; femur ; Ferengi ; fiber optic relay ; Fire Caves ; flow regulator ; " For He ' s a Jolly Good Fellow " ; frequency ; fungi ; God ; gravitic sensor ; hairbrush ; hairline fracture ; iceberg ; Idran hybrid ; imaginary patient ; impulse thruster ; Irish whiskey ; inertial coupling ; isolinear chip junction ; kiss ; " Koss ' moran " ; Leeta ; level 3 diagnostic ; level 3 stasis field ; Litana ; lunch ; Lupi ; magnetic constrictor ; night shift ; operating table ; optronic integrator ; orange juice ; pah - wraith ; pancake s ; parietal lobe ; phaser ; pineapple ; polarity ; Promenade ; Prophet s ; puree of beetle ; q ' parol ; Quark ' s ; radiometric anomaly ; " raktajino " ; repair log ; Replimat ; root ; rot ; Rudellian brain fever ; runabout ; sabotage ; sausage ; Shakaar Edon ; shock ; Starbase Sierra Tango ; slug liver ; stun setting ; swing shift ; Tellurian mint truffle ; temporal disruption ; verb ; waste extraction system ; water ; wideband filter protocol ; Yridian