Cardiff 1812: It’s late at night when an attractive prostitute, Mary, leads a soldier to a spot she knows deep in the woods. She and her friends have been busy since the regiment was billeted here, but she can sense this is his first time. When she stops and starts to undo his trousers, he slaps her viciously across the face. She taunts him and he slaps her again, so she scratches his face and runs off into the darkness. He chases after her, calling her a whore, but even as she loses him in the woods, she suddenly stops in pain when she hears an unearthly noise. There’s a strange glow coming from just ahead of her, but with the soldier closing in on her, she has no choice but to head towards it. Seconds later, the soldier appears and draws his pistol. He advances nervously towards the light and sees Mary standing in a clearing. As she turns to face him, he raises his gun and fires…

Present day: The Torchwood arrive at an large excavation site where the foundations of a new building are under construction. The area has been cordoned off and the police are also in attendance, but the group move straight through into a series of tents erected over the site. Behind the police cordon, several members of the public are trying to get a better view of what’s going on. Among them, is a beautiful young woman watching events with keen interest. It’s the prostitute Mary.

Jack declares that once - just once - he’d like to walk into one of these tents and find there’s a party going on inside. The rest of the group are examining a human skeleton that was unearthed during the building work, but Jack’s interest is focused on a strange looking device of alien origin with prongs that jut out from the base and point together in a triangular shape. It’s built from non-terrestrial metals and is even giving off traces of dark matter. He has no idea what it is - it could be a weapon, but then it could just be a really big stapler. Owen’s cursory examination of the skeleton suggests it’s a woman and the shattered ribs indicate she was shot. Tosh’s analysis of the soil shows that the body and the device have been buried for nearly 197 years. As Gwen helps Owen out of the pit, their bitchy flirting does not go unnoticed by Tosh.

Back at the Hub, Owen and Gwen continue to flirt as they work on the wiring underneath Tosh’s computer terminal. Tosh catches them and Owen is forced to reveal that her computer is dead. He tries to explain what happened, but it’s evident the damage was caused when he kicked out the plug during a football game. Tosh is furious as she may have lost all the work on the translation programme she was running to look for evidence of a common derivation between all the alien languages they’ve encountered. Her mood is not helped when Owen and Gwen start giggling over a private joke. She accuses them of being unprofessional and Gwen apologises, but Owen is less friendly and is openly rude to her face.

Tosh is depressed and goes to a nearby bar for a drink on her own. The young woman, Mary, approaches her and says that a guy in the corner has been staring at her all evening so she’d like to join her before she punches him and gets barred again! Tosh looks over at the man, but he seems to be innocently lost in his own thoughts. Nevertheless, Tosh agrees to have some company but when Mary offers to buy them both a drink, she addresses Tosh by name even though she hadn’t given it. Mary openly admits that she knows who she is - her name is Toshiko Sato, she was born in London in 1975, moved to Osaka when she was two, then came back to the UK in 1986. Her parents are in the RAF and her grandparents worked at the codebreaking establishment Bletchley Park. She went to University, then was snapped up by a Government think tank when she was 20 and was recruited to Torchwood three years ago. Mary tells her she was watching them at the building site. Tosh demands to know how she obtained information about Torchwood and Mary tells her it’s all on the inernet if you dig deep enough, and the rest she got from police radio scanners. She belongs to a group of scavengers or collectors, but they’re really just an unorganised and disparate group of IT guys who still live with their mothers. Tosh prepares to leave, but there’s something about Mary that makes her want to find out more…

Later, Tosh and Mary are more relaxed in a quiet area of the bar. Tosh has opened up to her new friend and is telling her about the work she does and how fascinating it is that so many alien races have similarities with our own culture. The down side is that they find so many weapons it seems every species wages war, as if it’s a trait of existence itself. On the other hand, she’s spent the last three months translating something they found which was covered in alien symbols which turned out to be a letter someone had written to their children telling them how much they were missing them. The realisation that even across unimaginable distances there are fundamentals that stay exactly the same made Tosh cry. Sadly, she has no one to talk to about it as the rest of the Torchwood group don’t see things the way she does. Tosh suddenly realises she could be fired for revealing so much. Mary gets something out of her bag - a pendant on a chain - and she invites Tosh to put it around her neck. Suddenly Tosh is overcome by a tremendous rush of voices inside her head. As a man walks passed, she can hear his thoughts as he plans to have one more drink and drive home slowly. Elsewhere, a woman is wondering about her diet; another woman is thinking about slapping her partner because he keeps stroking his groin; a man is worried about how many people he sent an email to…

Mary explains that they’re the thoughts of everybody in the immediate area, but they’re too loud for Tosh. When she hears a man wondering whether she and Mary are lesbians, she becomes overwhelmed and Mary tries to encourage her to focus on just one person’s thoughts - hers. By concentrating, Tosh is able to shut everything else out until the only voice she can hear in her head is Mary’s. Mary explains that it takes some practice, but by honing in one one person she can learn to control her new power. Tosh is snapped back to reality when she discovers her new friend wants to kiss her and Mary admits that sometimes she can’t control what thoughts she’s sending out. Tosh wants to know more about the pendant and Mary explains that it’s been in her family a long time but now she wants Tosh to keep it. She’s had it too long and after a while you hear too much and it changes how you see people. Tosh wants to show it to the others, but Mary just laughs. She knows Tosh won’t do that, no matter how much she insists that she will.

Tosh returns to the base…and just before she joins the others, she can’t resist the temptation to put the pendant around her neck. She can immediately hear Owen thinking to himself about the wounds on the skeleton as he takes a break from his examination. He greets her, then she hears him make an unkind observation about her constant complaining. Gwen also greets her with a smile, but her thoughts are on her old colleagues back in the police force. Tosh announces that she has something to show them, and Owen’s thoughts reveal that he hopes she’s not going to make them sit through another boring slide-show about the Incas. Gwen looks up at Tosh and thinks bitchy thoughts about her fashion sense. Owen is thinking about how weird Tosh can be, and then wonders what she’d be like in bed. Gwen is thinking about when she shagged Owen in his car earlier (for the second time!) and is wondering whether twice means they have a formal arrangement…? Owen also starts thinking about Gwen and has to sit down until his erection subsides. Gwen then thinks about luring Owen down to the cell area, but realises she doesn’t want to have sex in front of a Weevil. Their thoughts are becoming too much for Tosh to handle, so she makes an excuse about wanting to show them an article, but that it can wait until tomorrow. Another bitchy comment from Owen is the last straw and she leaves.

Later, she is sitting alone at her work station when Ianto arrives to collect some mugs. She can instantly hear the despair in his mind as he wonders whether the pain will ever go away. He feels so empty, as if there’s nothing more in his life than anguish and misery. There isn’t a single part of him that doesn’t hurt. He breaks into a smile and offers Tosh a cup of Jack’s industrial strength coffee, and she’s shocked at how different his outward appearance is to the turmoil going on inside his head. She rips off the pendant.

When she returns home, she’s not surprised to find Mary waiting for her outside. Mary asks if she told her collagues about the pendant and she admits that she didn’t. Mary follows her inside and asks her why she changed her mind and when Tosh doesn’t respond, she guesses that she must have listened to their thoughts. Tosh is distraught at the things she’s heard and shocked by the reality of what her ’friends’ really think of her. Mary assures her that her friends do like her, but people are complicated and it’s not like reading someone’s diary. The stuff Tosh has been hearing is so deep and personal, they’re not even aware they’re thinking it, but Tosh is still angry and dismisses her friends as “bastard kids”. Mary reminds her that not everyone is like that, and she gently replaces the penadant around Tosh’s neck so she can hear what she’s thinking. Tosh comments on the fact that Mary’s thoughts about her aren’t exactly pure, but at least she’s consistent and has no agenda or resentment. Tosh breaks down in tears as she realises her colleagues pity her. She notes that Mary’s thoughts are starting to become graphic, but Mary points out that they’re not her thoughts at all - they’re coming from Tosh herself. The two of them are starting to think alike, which disturbs Tosh…but when Mary moves closer, they share a passionate kiss.

Tosh is alone in bed, in a state of shock. Mary emerges from the bathroom and gets back into bed with her, but Tosh is freaking out a little and they end up sitting upright with their backs to each other. Mary notices her friend still has a birthday card on her table from Owen, even though her birthday was a long time ago. She guesses this is the same Owen from work, whose photograph adorns Tosh’s fridge. She mocks her and says she doesn’t want to get in the way of anything that might be going on between the two of them. Tosh doesn’t want to talk about it, but Mary says it isn’t the first time she’s been a rebound shag. Thanks to the pendant, Tosh now realises she’s never going to get together with Owen and she climbs back into bed, huddling up in a protective position. Mary brings the pendant over and tells her it’s capable of some extraordinary things, but when Tosh says she can’t imagine any good coming out of it, Mary encourages her to go somewhere public and stand amongst the hustling crowds. Tosh doesn’t know what she’s supposed to be looking for, but Mary assures her it will find her. Tosh is sick of her riddles and demands to know who she really is. Is Mary even her real name? Her friend smiles and suggests another name - Philoctetes.

Tosh goes out into the main Cardiff shopping area and stands in the middle of the pedestrian area as shoppers and workers mingle around her. She puts on the pendant and is momentarily overwhelmed by the mass of voices in her head. She starts to focus on individual people and hears a passer-by planning to forge someone else’s signature; a man trying to make sure his wife doesn’t discover he’s been putting on her underwear; a woman counting how many post-coital cigarettes she’s had today; a man who likes to imagine he’s James Bond…but then a man walks by repeating over and over in his head that he’s going to kill some people! He plots out in his mind how he‘s going to lay their bodies out and then kill himself so that his body is found lying next to them. Tosh is shocked back into reality and desperately looks around to see whose thoughts she was hearing. She identifies a man carrying a bag that might easily contain a shotgun. His thoughts reveal that he isn’t going to miss anything about his life, so she starts to follow him…

The man with the shotgun, Neil, knocks on a nearby door, which is opened by a bored boy playing on a computer game. Neil is evidently upset that his son, Danny, is showing no interest in him and is particularly annoyed when his ex-wife Carol calls out from the kitchen that he has to bring the boy back by six o’clock. She has an appointment at the tanning centre as a present for her forthcoming wedding and he’ll be breaking the law if he brings Danny back any later. She adds that her dad reckons she could have him arrested if he does it again. Even his son reveals that he doesn’t want to go with Neil and when Carol starts to talk about how much he loves his new ‘dad’ Laurence, Neil snaps. He pulls out a shotgun from the bag and loads it in front of his wife and child. As they cringe in terror, he recalls an incident earlier in their relationship when she used to think he was her hero. It’s his perfect memory - they were happy just being together. He forgives her for all this nonsense with Laurence because he can see the bigger picture now. He raises the gun to his wife and she screams when he says they can now be together forever. Suddenly Tosh appears behind him in the hallway and knocks him to the ground with a golf club. For a moment everyone is stunned, then Tosh assures Carol and Danny they’ll be OK now.

Tosh returns to the Hub and find the group has assembled together in the autopsy room. The mood is light and Gwen is especially enjoying the moment as she mocks Owen for a mistake he’s made. Slowly she teases out of him a confession that his earlier examination of the skeleton from the building site was somewhat flawed. Not only was the victim not a woman, he wasn’t shot either. He reminds them that his initial conclusions were formed after only a cursory check, but he admits that he’s had to ’tweak’ some of his findings. Tosh is confused when the cause of death is given as unidentified trauma, but Gwen explains that this term refers to something entering a body at great velocity and is often used to describe wounds suffered in a road traffic accident.

Jack leaves Gwen and Owen to continue their teasing as he needs to make an urgent phone call. Tosh joins him and asks if he knows anything about Greek mythology - in particular whether he’s heard of someone called Philoctetes. She claims it came up in a pub quiz, which Jack finds a little surprising. He explains that Philoctetes was an archer recruited to fight in the Trojan War, but he had an argument and was marooned on the Island of Lemnos for about ten years. As she leaves, he reminds her about a list she’s supposed to be preparing for UNIT and he asks her to get a move on. He then returns to his telephone call to the Prime Minister, rebuking him for including details of Torchwood operations as part of his security briefings to the leader of the Opposition.

Tosh joins Mary in a nearby café and they discuss what happened with the man who planned to kill his family. Mary thinks Tosh is unbelievably brave and sexy and says they should make an action figure of her, and Tosh finally accepts that the pendant can be used for good. Mary is pleased that Tosh didn’t reveal any of this to her friends at work and insists on kissing her in public. Then Mary asks what’s happening with the device they discovered on the building site and is disappointed when Tosh says she hasn’t been told anything. She finds this odd as Tosh is supposed to handle all the technical stuff, but at the moment she says she’s busy with an admin job. Mary hints that Tosh’s boss must be keeping things from her for a reason and Tosh starts to wonder if there’s any truth in what she’s said…

Tosh returns to the Hub again and finds Owen still examining the skeleton in the autopsy room. If the wound wasn’t caused by a gunshot, then what could have done it? He theorises about devil worshippers from that period, but there’s no record of them having anything to do with plucking out people’s hearts. They ate eyeballs, they drank blood and they had sex with animals, but they don’t appear to have had a ritual for heart plucking. Tosh wonders why he’s bothering since it’s unlikely to be a threat to society any more, but Owen needs to find the answer. He finds her presence unhelpful and tells her to go back to her computer and think about shoes, but before she leaves she asks him whether Jack said anything to him about the alien hardware they found. Tosh says he hasn’t and when she puts on the pendant to hear his thoughts, she discovers he’s telling the truth. Gwen arrives and Owen makes a deliberate point of ignoring her, causing her to wonder if she‘s done anything wrong. Tosh has had enough of listening to the two of them thinking about sex all the time so she storm off back to her desk.

On the way she sees the alien device on a nearby table and she goes for a closer look. Jack arrives and tells her he’s just had a really interesting conversation with Detective Inspector Henderson who told him about Tosh saving a woman and her son from being murdered by her ex-husband. He wonders why she didn’t tell anyone here about it, but she says it just wasn’t a work thing and she didn‘t want to look as though she was showing off. Jack points out that the police report indicates she was tipped off when she overheard the man muttering to himself as he passed her in the street. He queries how unlikely it would be that a potential killer would talk to himself about his plans while he’s walking around in public? She changes the subject and asks him about his investigation of the device, but all he’ll say is that’s it’s ongoing. She tries to listen to his thoughts - and is shocked to discover that she can’t hear anything at all. It’s as though his mind was completely blocked to her. Suddenly he stares at her as if he can sense that she’s trying to read his thoughts. She makes an excuse to leave, and Jack ponders what’s just happened…

Mary has moved in with Tosh and she returns home with food and drink for the night. Tosh reveals that she’s decided to give the pendant to her colleagues because hearing their private thoughts is making her feel dirty and ashamed. She feels like she’s spying on her friends, but Mary questions whether they really are her friends. She reminds Tosh that they pity her and exclude her. They even have her doing their admin. Tosh thinks Mary is worried they’ll ask about her and she assures her they’ll only be interested in finding out more about the pendant. When Mary says that if she goes into Torchwood she’ll never come out again, Tosh decides to call Jack - and Mary orders her to put the phone down in a booming alien voice. It’s too late to pretend any more and Mary reveals what Tosh has now started to suspect - she’s an alien! Mary’s body begins to break up and a glowing light emerges from within her. As the light fades, Tosh can see the real Mary - a giant female creature with translucent skin revealing a bright skeleton inside. Tosh gently reaches out to touch the alien’s hand and discovers it is cold. The alien assures Tosh she’s still the same person she kissed…and then she reverts back to the form of ’Mary’. Tosh is shocked that she’s been shagging an alien and a woman, and Mary wonders which of the two is worse.

Tosh realises that although she’d read Mary’s thoughts she didn’t see this coming and is concerned about what else her friend might be keeping from her. Mary explains that when she first arrived on this planet she thought the freedom people enjoyed was almost obscene. Her home world was savage, with enforced worship in temples the size of cities and execution squads roaming the streets. Dissent of any kind meant death or transportation to what they called ‘feral outposts’. The pendant is how her people communicate and they consider that normal speech using a finite number of words is archaic and gross to look at. The machine Torchwood found is a transporter which brought her here and can take her back home again. She needs it back before it’s dismantled. She believes she’ll be safe now as two hundred years have passed since she left her world and in that time they’ll have been several new Governments. Tosh wonders why no one came back for her and Mary says she’s been forgotten, like Philoctetes on Lemnos. Tosh offers to take her to Torchwood to see if they can help her, but Mary believes she’ll be ’examined’, assessed to see whether she’s useful or a danger, and then locked in a cell. She’s convinced they’re not interested in understanding alien cultures. It’s just as well humans don’t have the technology to reach other planets yet as they have a culture of invasion! She has no intention of walking into that with her hands raised in surrender.

Tosh wanders the streets of Cardiff, alone and deep in thought. She continues to hear voices in her head and she becomes increasingly distressed at some of the secrets she’s discovering - people who batter their partners, others who were abused as children, and those whose lives are empty and without meaning. She rips off the pendant in disgust.

Owen is still unsure as to the cause of the unidentified trauma that killed the man found in the building site. Eventually he gives up the medical examination and is about to go home when he decides to conduct some research on the computer database. He hacks into the Cardiff General Hospital computer and searches through the records of some recent cases… After some time he comes across a medical record of a patient named Lucy Marmer - a 43 year-old woman who was brought in dead on arrival in September 2001, suffering from shattered ribs and with her heart removed. The records indicate that details of the post mortem were passed to police officers assigned to something called Operation Lowry. He uses Torchwood authorisation to access the police database and discovers details of other unsolved murders in the area where the victims had similar wounds: Joyce Saville in 1982, Iffy Okoli in 1978, Lee Ball in 1976, Melanie Gough in 1974, Richard Playle in 1973, Sally Chappel in 1972, Myra Bennett in 1970... How far back does it go? He calls Jack and tells him he’s found something he has to see.

Tosh lies back on her bed and ponders her current state of mind. She can’t stand the weight of it any more - the depravity and fear that fills her up…it’s like she’s drowning…and even when she doesn’t have the pendant on she can’t forget the things she’s heard. It’s like a curse, something the Gods sent to drive someone mad. She’d hoped she’d see some random act of kindness to make her think she was safe, that there’s some good in us - but there isn’t. Look inside us and you see one great scream. She tells Mary she was right about everything she said. The human race is frightened and callous and Tosh doesn’t want to be part of it any longer. She begs Mary to tell her what to do - and the alien orders her to help get her into Torchwood.

Tosh escorts Mary through the security systems and into the main Torchwood Hub. The alien is truly impressed and recounts “The Ballad of Kubla Khan”, a poem by Samuel Taylor Coleridge: “In Xanadu did Kubla Khan, a stately pleasure-dome decree, where Alph, the sacred river, ran through caverns measureless to man, down to a sunless sea.” She asks her to collect the device quickly as she has a long journey ahead of her…and she might need something to eat before she goes. Suddenly Jack appears at the top of the upper level, holding Mary’s transporter device. Tosh wonders what’s happening and Jack explains that he once had a friend called Vincent, a regular guy with a girlfriend. He liked his beer and his sport, but then one day he started acting strangely and became distracted. He disappeared for a while and when he returned after a couple of months he wanted everyone to call him Vanessa. Ever since then Jack has always been a little nervous when friends starts behaving out of character. Jack holds up the device but Tosh already knows what it is - she tells him Mary is a political prisoner who was exiled here, but Jack corrects her on part of the story. It’s actually a two-man transporter and is intended to be used by both the prisoner and the guard. Mary confesses to killing her guard, but then she was disturbed…

Back in 1812 the alien creature has just landed on Earth when the prostitute Mary arrives after being chased through the forest by the soldier. Sensing her presence, the alien floats across the clearing and then possesses Mary’s body… Seconds later, the soldier also arrives and sees Mary standing in a clearing. Believing her to be the same prostitute he attacked a few moments earlier, he raises his gun and fires - but the bullet goes straight through her. Then the alien floats across the clearing and plunges her new hand into the soldier’s chest and plucks out his heart.

In the Hub, Tosh and Mary find themselves surrounded by the rest of the Torchwood group who’ve been in hiding. Owen realises she’s been plucking out people’s hearts ever since she first landed here and Mary explains that she needs to feed. She fled the forest before any more soldiers came and over the years she came to learn that her beautiful body had a power over other people. In time, the forest was built over and the transporter was safely buried under the spread of the city. She was in no hurry to leave Earth, but she always knew that her position here might become complicated and she kept an eye on the area so she’d know where the transporter was in case she needed it. When the device was uncovered during the recent building work, she could sense the moment when the air touched its surface.

Tosh puts on the pendant and starts to listen in on her friends’ thoughts. Gwen has noticed that Mary is watching Tosh with the eyes of an animal, while Owen is thinking back to his time as a junior doctor in 2001. He’d only been qualified for six months when Mary’s victim, Lucy Marmer, was brought in. He’s about to grab her - but Tosh hears his voice in her head and calls out to him to stop! In a flash, Mary floats across the room and appears next to Tosh, holding a knife at her lover’s throat. Jack pleads with her to let Tosh go, but Mary orders Tosh to persuade them to hand the transporter over. The hostage situation reminds Ianto of his recent loss, while Gwen is using her knowledge of knife wounds to predict the injuries Tosh will suffer if Mary goes ahead with her threat. Mary offers to exchange her hostage for Gwen and says the choice is Owen’s. It soon becomes clear to everyone that Mary and Tosh have been able to read their thoughts. Mary tells Tosh that whatever crimes she may have committed, it doesn’t change the way she feels about her and the two of them have a real connection.

Jack is able to send his thoughts directly into Tosh’s mind, overriding all the other voices she can hear. He tells her not to move until he gives a signal. He then offers Mary an exchange - he will give her the transporter if she releases Tosh. Owen can’t believe Jack is going to let Mary go, but Ianto suspects the device can’t work after all this time underground. Mary agrees to the swap and she frees Tosh. Jack hands over the transporter and as she takes it, it suddenly activates itself. Jack explains that he took the liberty of re-programming it and it’s now set to enable. The device begins to glow and energy beams pulse from it. Within seconds, both the device and Mary have transformed into a glowing ball of light which then zooms upwards and out of the building. Tosh asks if this means Mary has gone home, but Jack reveals that he also re-set the co-ordinates to send her directly into the centre of the Sun. He’s killed her and Tosh is devastated.

As Ianto debriefs Tosh in the interview room to bring their records up-to-date, Owen and Gwen wait outside and discuss the situation. They both want to speak to her, but disagree over when the best time would be. They’re creeped out by what’s happened, and although Gwen thinks Tosh has suffered enough already, Owen insists that they speak to her straight away. Tosh joins them and Gwen asks exactly how long she’s had the ability to read their thoughts? When Tosh tells them it was just a couple of days, Owen becomes angry and demands to know what she heard. She assures them it was mostly just a mixture of emotions, background noise and some references she didn’t understand - and she considers the rest of it to be none of her business. Owen agrees with that last point and storms off. When Tosh and Gwen are alone, they both accept that they don’t know where this revelation will take them, but Gwen knows she and Owen can hardly take the moral high ground. She tries to explain her relationship with Owen, but Tosh doesn’t want to know. What she did was an invasion of their privacy and now she has to live with what she did to them. Gwen looks over at Owen and realises she also has to live with her betrayal of Rhys. This should really be a ‘wake-up call’, but she’s already decided she won’t stop seeing Owen and wonders what that says about her. She and Tosh both agree that neither of them are in a position to make judgements about the other. As Tosh leaves, Gwen makes one final point. In the last couple of days she’s noticed that Tosh had a look about her - love obviously suited her, so she hopes this won’t put Tosh off in the future.