Day One ( TV story ) Day One was the second episode in the first series of " Torchwood " . Taking advantage of its post - watershed allowances , it was the first " Doctor Who " - related onscreen production to explicitly centre its conflict around sex . The episode explored sexuality in the 21st century , and took a look at an alien interested in something more than just enslavement . It saw Gwen Cooper take on her first mission for Torchwood , following her induction in " Everything Changes " . Synopsis . Gwen ' s first day on her new job at Torchwood sees Cardiff ' s night - life at the mercy of a gaseous alien who consumes its victims during orgasm , leaving behind only dust . And it ' s all her fault — she let it escape a fallen meteorite . The gas is devouring its teenage host . She ' s fighting for control as the alien inside takes down victim after victim . Torchwood tracks the alien to a sperm bank , but too late for the patrons within . Soon , if they don ' t act quickly enough , it ' ll be too late for everyone else too ! Plot . Gwen is having dinner with Rhys , after bowling and a movie . He asks her about her new job at Torchwood . Gwen lies , saying she will mostly be handling filing . A meteor falls through the sky and Gwen notices it crash on the town ' s outskirts . They run to get a better view , then Gwen gets a message and tells Rhys that she has to go to work . Gwen is picked up by the team in the Torchwood SUV , commenting on the dual computer stations and a seemingly illegal link to the police CRIMINT computer system . They arrive at the crash site and find , to their disappointment , that the " amateurs " — the British Army — have beaten them there . Jack tells the team to employ the " usual formation " ; Owen informs Gwen that the usual formation varies . While the rest of the team head to the meteor to examine it , Gwen remembers her equipment and returns to the car to get it . Army security stops Gwen until Jack comes back to collect her and tells them to back off . The others move into action , taking samples and readings , and Gwen feels inexperienced and out of place . When Owen starts trying out nicknames , the least of which is " New Girl " , and asks for a bigger chisel to help get a part of the meteor , Gwen cracks a joke about Owen needing a bigger tool for the job and tosses the chisel at him . She misses . It punctures the skin of the meteor , and , as Jack tosses around gas masks , it begins to release a purplish gas that coalesces and rises into the air . Gwen looks around at her team guiltily . At an alley near an underground night club in Cardiff , a young woman , Carys Fletcher , is leaving a distraught voice mail for Eddie , who she says has stood her up again for another woman , when she is confronted by the gaseous creature . It backs her against a wall , then flows into her body . Carys , confused and shocked , inhales the Sex Gas through her mouth and nose . After all of the gas was inside of her body , she exhales . She suddenly goes from upset to sexually aggressive , and gains re - entry into the club by kissing the bouncer . She picks out a man , Matt , and nearly drags him into the women ' s toilet . They have sex , and , at the moment of climax , Matt dissolves into a glowing cloud of dust , while the energy portion of Matt is absorbed by Carys . Gwen keeps apologising , Owen keeps taunting her , Toshiko wants him to lay off , and Jack just wants her to get past it and back to work . Ianto thinks he can help , as he ' s heard an unusual 999 call for the nightclub . The team investigates , and PC Andy is surprised to see Gwen . They find the dust and the CCTV tapes that show Carys and Matt having their deadly sex and the alien taking her over in the alley . Jack arranges for a body to be taken out of storage to fake a suicide for Matt , which shocks and dismays Gwen . Jack confiscates the tapes . While the team analyses the meteorite and scene data , Carys is feeling the effects of the previous night . She spends most of her dad ' s breakfast monologue staring into the distance , claiming a hangover . Gwen tells Tosh , Owen , and Jack about Rhys , and finds the other three don ' t have time to date . Tosh tries to track Carys by cross - checking video from the surveillance cameras with a database of the faces of the UK population . Meanwhile , Carys breaks down crying in the shower . As she brushes her hair afterwards , she is racked with pain several times as she stares into the mirror . The postman arrives and Carys pulls him into her house , throwing him down on the couch and pulling at his clothing , but the team arrives before she can do the deed . She breaks away but Owen catches her with an alien device that he didn ' t have permission to carry . After dressing Carys and bringing her to the Hub , Jack puts Gwen in charge of interrogating her . In a holding cell , a consciousness takes over Carys momentarily . It tells Gwen it is not here for conquest , but to feed off human orgasmic energy . Carys pleads for help and doubles over in pain , causing Gwen to open the door and help her up . However , the alien presence takes over and Carys kisses Gwen . After pulling herself away , Gwen suddenly begins passionately kissing Carys . In the main Hub room , Owen notices this on a monitor and is amused . He informs Jack and Toshiko , calling it a " treat " . Back in the cell , the presence in Carys realises it needs a man for its energy . Carys breaks through and pleads for Gwen to help her . Gwen regains her senses , walking out of the cell and locking it . Gwen receives a call from Rhys just as Jack and Tosh arrive to help get her away from Carys . She signals them that she is all right and vaguely tells Rhys how her job is going so far . Returning to the main Hub area , Gwen is confronted by Owen , who jokingly congratulates her on her " methodical investigation " before telling another dirty joke . Angered at Owen ' s lack of care for Carys ' plight , Gwen pins Owen to a wall and yells at him ; they should be helping her instead of studying her like a lab rat . Jack breaks it up , saying that throttling Torchwood staff is " his " job . Ianto shows up with dinner . At dinner , they all laugh over alien anecdotes until Jack excuses himself for the restroom . Ianto , Owen , and Tosh quickly ask Gwen if she has learned anything about Jack yet . Gwen ' s surprised they ' re asking her , but they know nothing , except that Owen believes Jack is gay , which Tosh diagrees with . Tosh thinks Jack will go for anything if it ' s beautiful enough . Ianto doesn ' t care . They ' re not even sure he ' s America n , as Tosh found no US citizen by his name born in the last 50 years . Ianto thinks he ' s CIA . Gwen hears a faint crying and notices Carys on the monitor , and Jack returns . She tells Jack that they should be doing something to help her . Jack explains the scans , tests , and searches that Gwen didn ' t know were already running . They are doing everything they can think of to analyse the problem . Gwen explains , " You ' ve been hidden down here too long , spending so much time with the alien stuff , you ' ve lost what it means to be human . " Jack challenges her to show him " what it means to be human in the 21st century . " Gwen creates a complete profile of Carys ' life , and Jack is curious about why Gwen put such effort into it . She insists Carys is not a threat , but someone in trouble who needs their help , and the information can help them help Carys fight the alien influence . Jack is momentarily speechless , and calls her brilliant , until she asks to bring in Carys ' dad . Tosh breaks up the discussion with the results of the tests . The alien in Carys is producing a cloud of pheromones around her , turning her into a walking aphrodisiac . They can ' t let Carys near any man and realise Owen has gone down to her to get medical scans . They arrive to find him naked and cuffed in the cell ; Carys took Owen ' s swipe card after the pheromones overpowered him . Toshiko tells Owen that he ' s very lucky that his card is all she wanted and frees him . Gwen asks if Owen is okay then cracks a joke at his expense . The possessed Carys , meanwhile , makes her way to the Hub ' s exit and is confronted by Jack . They battle with the ambient weaponry until she takes the mysterious hand hostage to keep Jack from following her to the exit . However , Jack soon catches up through a secondary exit . Even though Ianto offers to help , Jack opens the door in exchange for the hand , which Carys hurls to the floor . The ladies give chase and lose her in the plaza . Gwen berates Jack for caring more about a severed hand than a girl ' s life . After Owen dresses himself , he demonstrates the results of his bio - scan of Carys on a rat showing that the physiological effects of the gaseous creature will make the body literally explode if it inhabits a person too long , dubbing the end result " Rat Jam " . They then wonder where Carys could be as the alien in her wants orgasmic energy . Owen then jokes if he was possessed by the alien he ' d come after Gwen , much to everyone ' s annoyance . Tosh then comes up with an idea . The alien in Carys walks a street in a shopping district , in a daze of overwhelming sexual imagery . She drops in on her now ex - boyfriend and attempts to hold back the alien influence . After she learns her ex was only using her , she lets the alien kill him . The team arrive later . Jack makes a joke about his numerous exes . While driving through town , they discuss how to stop the alien before Carys dies . Gwen double checks the records , finding that she is working as a receptionist at Conway Clinic . Owen recognises it as a fertility clinic , an ideal source of orgasmic energy . They also determine that the alien takes hosts because Earth ' s atmosphere is poisonous to it . Jack gives Gwen a gun , and is surprised when she protests that she ' s never used one . Carys is already at the clinic , dragging the sperm donors into the private rooms . When the team arrives , there are piles of dust everywhere . When they surround her , Carys collapses , too weak to fight the alien any more . Jack kisses her , and she glows as he gives up some of his life force to revitalise her , confusing Tosh and Owen . Carys faints . Gwen offers herself as a host for the alien , asking the alien to spare Carys . Gwen backs away , and the alien flows out of Carys ' body . Jack drops a portable prison cell and traps it inside before it can reach Gwen . Separated from its host , the alien dies , falling into a pile of dust . Gwen kisses Jack in thanks for saving her life , causing Jack to pause and consider after she leaves . Gwen and Jack take Carys back to her father . As Gwen clears up , Jack asks her to keep perspective on the job . She challenges Jack to come clean . Jack says the answers to her questions won ' t make her feel better . He asks her to be normal , for him . Gwen has dinner with Rhys , then they go to bed .