Robert fights his way through the storm, battling against the rain and the mud, until he arrives at the old secluded house across the river. He bangs on the door and pleads to be allowed in, and eventually the front door creaks open, apparently of its own accord, and he steps inside, apologising for intruding in such a state. The door slams shut behind him and an elderly woman invites him to sit by the fire. She tells him the boatman should have known better than to let him cross the Fens on a night like this, but the young man says he paid her well to bring him here.

The old woman, who Robert addresses as Miss Kingdom, prepares some hot broth for him. He tells her it’s quite a feast, but she says Ely was once farmland and the people here grew more food than they could eat. Robert is sceptical and says he’s never seen any evidence that this was true. He reveals that he’s a scientist who doesn’t believe in fairy tales or ghosts, but she says there are a hundred stories she could tell him from her time running this guest house. For example, there was a woman, Mrs Palmer, who arrived with one husband but left with another. Robert seems impatient and says she knows which particular story he wants to hear - the one about the house of dreams and magic. Miss Kingdom already know that Robert probably won’t believe her story, but he insists she tell it anyway.

The story took place a long time ago, when Miss Kingdom was a different person. She was young and sure of herself, but then she met the Doctor and Steven and suddenly she was no longer certain of anything. She was an agent of the Space Security Service, a sort of night constabulary that had grown so powerful it had become complacent. The Doctor and Steven were criminals and she’d been sent to kill them - her orders were to shoot first and ask no questions - and Steven was exasperated that she’d been willing to obey them without thinking. There was a moment when Steven and the Doctor were entirely at her mercy, but then things were turned upside down when her brother was killed. Bret was the reason she signed up in the first place and she’d carried his memory with her ever since, allowing her to see things the way he did. Sometimes she could almost fell him physically standing beside her, judging her, but saying nothing. By the time she discovered her whole life had been a lie and that her orders were intended only to ensure that the Guardian’s dark secret remained safe, she‘d already made a terrible mistake. After that, she became a criminal herself and went on the run with the Doctor and Steven, travelling from place to place, trying to find sanctuary from creatures without mercy.

Robert is sceptical, but says he’s prepared to suspend his disbelief for now and asks her to continue.

She tells him of the forest of invisible beings and then the three of them travelled to the world where the Doctor’s ship was waiting. After that, they experienced the poisonous air of Liverpool on Christmas Eve and a town called Hollywood. Then she remembers the small boy who died in her arms as they looked out over the Martian landscape, and the withered old man who was caught up inside the workings of a clock. And then there was the house…

The TARDIS materialised inside a modern-looking kitchen. It was impossible to tell how old the house was or why it was built, but it was immediately clear that a lot of care and craftsmanship had gone into it. It felt warm like a summer’s day, there were soft comfortable carpets throughout, and the kitchen looked brand new, with gleaming surfaces and polished chrome. Until she began travelling with the Doctor, Sara had lived a very sheltered existence and came from a time where people were crammed into tiny domestic cubicles. She assumed a house this size must have catered for hundreds of people, so she was surprised to learn that it was probably home to a single family. The Doctor found a series of photographs on the wall showing a young, happy couple. They appeared to be newlyweds and this house presumably signified the start of their new life together. Sara hoped this place would offer them the sanctuary they were looking for, but the Doctor could instantly sense something was wrong here, as if there was a presence in the room with them.

Sara shuddered and then turned to see a glass of water on the kitchen surface that hadn’t been there a moment earlier. Steven examined the nearby sink and the taps turned on and off of their own accord. The Doctor assumed it was activated by a hidden sensor, but it wasn’t long before they discovered the house was actually responding to what they were thinking. Confident he could control things through the power of his own will, the Doctor strode towards a door leading to the rest of the house - only to bump straight into it when it remained resolutely closed. The Doctor remained convinced his theory was right and that he just needed more practice to make it work, but in the meantime Sara found a hand-shaped indentation on the wall that she thought was a more likely means of opening the door. However, it seemed to have no effect when she tried it and the Doctor rebuked her for not taking her lead from him. Steven did eventually manage to open the door by the power of his mind, but presumably because Sara was standing closest to it when it opened, she was the first to feel the strange effect, like static in the air just before a lightning storm. A bright light blinded her and she fell backwards, paralysed.

Sara recovered and found herself being held upright by Steven. The Doctor comforted her and said that because the house was so new, it was still full of static, and she must have got a shock when she touched a metal surface. Sara agreed, but she could tell the Doctor knew this wasn’t the real answer. The shock wasn’t caused by static at all, but by something in the air that had reached out to touch her.

Robert wonders if Miss Kingdom is claiming to have been touched by a ghost, but she mocks him for not believing in anything that he can’t prove for himself. He admits that he thinks her references to appliances that can read your thoughts and walls that can read palms are just narrative devices conjured up just to illustrate the story. He suspects she’s told this story so many times before she can no longer tell which bits she’s embellished over the years. He assures her that science doesn’t allow for such magical things to exist, but he says that’s not important and he wants to hear the rest of the story anyway.

The Doctor, Steven and Sara were now able to explore the rest of the house - and that’s when they found the first body. It was the young woman from the photographs. She was wearing brightly coloured clothes, but no shoes, and Sara concluded that she was preparing for bed - in which case she wouldn’t have been expecting trouble and was vulnerable. There were no marks on her and it seemed as if she’d only just died, perhaps even in the seconds before they entered the corridor. Sara realised the man’s partner might also be somewhere in the house and she wasn’t looking forward to telling him the woman was dead. As an officer, her life had been spent putting right things that had gone wrong, but despite being told in training that she’d become immune to seeing people killed, she knew that wasn’t true and she still felt each death like a blade going through her. Each new death weighed her down and threatened to be the one that broke her.

They left the woman where she lay and started looking for other man who they‘d seen in the photographs. They moved up a wide staircase littered with flowers and paper-wrapped gifts, wedding presents whose labels suggested the couple were Richard and Alex. There were rooms at the top of the stairs and they soon found Richard’s body. Again, there were no signs of a struggle or of what had killed him, and he even had a smile on his face. Steven suspected some sort of gas or poison in the air, but the Doctor was sure that wouldn’t have killed them both so peacefully. There was no sign of panic or realisation on the bodies’ faces and they appear to have died instantly and at the same moment, without even knowing it.

The Doctor suddenly asked Steven and Sara if they’d felt anything in the air, like someone drawing breath, but neither of them had. They all knew this was too neat to be a case of routine murder, but neither did it feel like a freak accident as everything seemed too painstaking and designed. Sara admired Richard’s jacket and then she noticed it was a couple of sizes too large for him, which was odd as the rest of the house had evidently been tailored specifically for the dead couple. They decided the only thing they could do was alert the local authorities and then conveniently disappear before anyone arrived. As they turned to leave, Sara felt something in the air, like someone breathing. She called out, but there was no response.

They moved quickly through the rest of the house, looking for a means of contacting the outside world. They saw rooms full of musical instruments and games and Sara felt the house was like a palace and that it contained far more than Richard and Alex could possibly want for. It wasn’t like a house she’d ever seen before and it was more like exploring a dream or a child‘s fantasy of the perfect home. Although they found an office downstairs, there was nothing to suggest the couple worked for a living and it was more like the house provided for their whims. Sara even wondered if living such a privileged life had made the couple targets of envy, but there was no evidence to support that theory. She found an old-fashioned anachronistic telephone, but when she picked it up out of curiosity, she heard a ghostly breath on the other end. She tried to report the emergency, but then the line went dead. Sara assumed her mind was playing tricks on her, but she knew that whoever or whatever had killed the couple was probably still in the house with them.

Robert tells her he’d had gotten out of the house as fast as he could. Miss Kingdom mocks him, reminding him that he claimed to be a rational man of science, but he says the evidence pointed towards the fact that they were all in danger.

Steven began to panic when they discovered they couldn’t open any of the exterior doors. The Doctor theorised that the house might be a tomb, sealed off and frozen in the moment that the people here died. Perhaps the couple had been dead longer than they’d originally thought and had been preserved. A terrible injustice had been done here and neither the Doctor nor Sara wanted to leave while questions remained unanswered, but Steven said it was putting them all in danger. Suddenly all three of them felt something in the air, as if something watching them from upstairs from where they’d just come. They headed back up to investigate and Sara balanced her feeling of dread against the challenge it presented.

Miss Kingdom continues to act the perfect host and offers more sustenance to the young man, but this makes him uncomfortable and he says he’s not used to being waited on. The old woman is surprised as she knows Cambridge used to provide its officers with support staff, but Robert says that was 100 years ago. He asks how she knew he was an officer and she tells him the silver stripe on his tie is the one used by magistrates. The guest house has catered for quite a few officers over the years and they always came to hear this particular story or to ask questions about it. One man even sat here and ate his broth, then just left without saying a word, but she could see from the way he was weighed down by the trauma of war and all the souls he’d lost that her story was the least of his problems. Robert thinks this must have been a long time ago as although they’re still trained as soldiers, officers haven’t had to fight for generations. She asks him what he’d do if he was called up tomorrow and he says he’d have to use his judgement to decide whether there was a good enough reason. In any case, he’s sworn an oath to destroy those deemed to be a danger to the church and state. Miss Kingdom wonders whether that includes her. The young man admits that he hasn’t decided yet and would rather hear the rest of the story first…

Sara rushed to the spot where Steven disappeared, but there was nothing there, not even the tang in the air that you normally get with disintegration. The Doctor reassured Sara and told her whatever they were facing, it didn’t mean them any harm. If it did, it could have killed them any time it wanted, but instead, it’s just taken Steven and put him somewhere else. They wouldn’t leave without Steven and they still had the rest of the house to explore, so his disappearance just made them more determined than ever to solve the mystery.

Sara decided to unwrap some of the wedding presents and found all the usual gifts you might expect. She scrutinised them for clues or inconsistencies, but there was nothing to help her unravel the knots. The Doctor was still intrigued by the fact that the dead man’s eyes closed after they first found him and said it seemed almost like an afterthought that was added later. Sara started to feel guilty and wondered whether it was her momentary wish that Steven wasn’t here to hamper her investigation that caused him to disappear. She heard the breathing again and then, for the first time, she actually saw something in the air. It was spindly, with invisible tendrils reaching deep into the shadows…and in that moment, Sara finally realised what had happened here.

Robert has already worked out that the killing and the closing of Richard’s eyes were done by different people. This is the inconsistency her younger self had been looking for - if the killer had wanted to close the eyes, he or she could have done it when they killed him. Miss Kingdom is delighted and suggests the man is starting to enjoy working out the puzzle. Robert thinks he knows the answer, but it depends on the story obeying the rules of fairy tales - like people who make wishes that don’t come out quite right. Miss Kingdom agrees - the house is always listening and it’ll provide a glass of water before you ask for it, and will open and close the doors whenever you want them to…but people want other things too!

Richard and Alex didn’t need the wedding presents as everything they wanted could just be wished into existence. There was no evidence of anger, a struggle or even an argument. It may have been as simple as Alex just calling up to Richard in a slightly nagging tone, or perhaps Richard said something that didn‘t quite come out like he‘d meant. Sara thinks it was probably Alex that made it happen, perhaps she was getting a bit annoyed because Richard was doing something in another part of the house when this was the first moment they’d had to themselves and he should have been with her. It wouldn’t have been anything as articulate as having a thought, it would just have been a nebulous sensation. And how would she have reacted when she realised what had happened? Sara imagined Alex screaming to the house to take back her wish, but there would’ve been no response. She wonders how long it took Alex to realise she was responsible, and how long after that before she realised there was only one other thing she could wish for.

Then the house was left with no one to look after or provide for. It may have sought instructions from outside, but perhaps the building had been condemned once the authorities knew what it had done? Maybe they’d tried to smash it down or burn it, but perhaps the building itself knew it had done wrong and decided to seal the doors and windows and break off all outside connection. Perhaps it then stilled the air, effectively stopping time. It may have been like this for years until the Doctor and the others stumbled in, causing time to begin again. Then the house did the only thing it knew - it tried to grant their wishes too…

Steven had suggested going back to the TARDIS, but Sara didn’t want that as she’d rather stay until they‘d solved the mystery. In that moment, just for a second, she wanted Steven to be somewhere else - and so he was snatched away. It was she who subconsciously wanted Richard’s eyes to be closed after they’d first found the body. It was she who thought there was a strange unsettling atmosphere in the house, causing the house to create an nebulous impression that there must be a monster locked inside with them.

As soon as Sara realised what was happening, she tried to wish Steven back, but it didn’t work. The Doctor gave her some techniques for focusing the mind and they both tried to conjure up the same image of Steven being back with them, but it seemed that the house was fighting back. They could both feel it in the air and Sara saw a corporal presence reaching out for her and forcing itself into existence. Then she heard a ghostly voice telling her she couldn’t have her companion back. Sara didn’t believe in ghosts and even hated fairy tales as a child, so she refused to believe Steven was lost to them. The Doctor told her the house wasn’t actually alive, it just had extraordinary powers - but the fact that it couldn‘t think like they could made it very dangerous. He was determined to shut the house down, but he also realised that the house would now see him as a threat.

They couldn’t be sure why the house hadn’t already been shut down from the outside, but it seemed logical to assume it was protecting itself. The Doctor said he had equipment in the TARDIS that could draw the ‘ghost’ out of the house and contain it, so he and Sara headed back to the kitchen with the Doctor helping to focus Sara’s thoughts so that her subconscious mind didn’t summon up things to come between them. As they passed the body of Alex again, Sara almost had a careless self-righteous thought, blaming the young woman for what she’d inadvertently caused, but the Doctor predicted this and prevented it before she’d even thought it.

As they approached the TARDIS, the Doctor let go of Sara’s hand to find his key and she felt it was like losing her grip on a lifeline. She tried to focus her mind, but she couldn’t help herself thinking that caging the ghost like a genie in a flask was somehow cheating. For a moment she wished the Doctor wouldn’t do it - and then suddenly the Doctor trapped between huge sheets, like invisible walls. He and Sara both banged on the glass, but to no avail. Then they realised the glass booth was starting to shrink. Sara searched through the drawers in the kitchen and found a wooden mallet. She struck the glass numerous times, but it had no effect and the trap continued to constrict the Doctor and press against his body.

Sara realised that right up until that moment, she’d been enjoying the challenge of the mystery and perhaps the house had latched onto that thought and was responding in the best way it could. She began to feel guilty for wishing these terrible things to happen. It was she who caused Richard’s jacket to change size because she’d thought for a second that it might look good on Steven. She wondered if she was being punished for shooting her own brother while he was trying to explain himself. She should have realised sooner that Bret would never betray the system and she wished she’d listened to him while she still could. But it was too late now and she realised the house was reflecting her guilt. It had looked deep into her mind and found a kindred soul. By punishing her for killing Bret, the house was punishing itself for killing Richard and Alex.

Sara noticed that the Doctor had stopped breathing and his eyes were looking back at her lifelessly. She knew she could no more bring back Steven and save the Doctor than Alex could wish back her husband, so she decided to take a mental step backwards to find a rational explanation by using the evidence around her to make the story work. She realised that if the house didn’t know any better, then it couldn’t be “punishing” her, so it must be doing something else. The house was struggling to put itself in order - it didn’t want to be destroyed, it just didn’t know how to read people or tell which wish to grant and which to ignore. It was like a child. Sara rushed back to the indentation in the kitchen wall and placed her hand into it. There was no pulse of energy or anything to indicate that the house even knew she was there, but somehow she knew it had been trying to grant her wishes ever since she first put her hand there. She concentrated hard and for the first time since they arrived, she knew what she really wanted…

Robert asks Miss Kingdom whether she asked for forgiveness, but she tells him that nothing can ever put right what she did to her brother. The young man says she’s being very hard on herself and thinks she must have shared her brother’s sense of right and wrong with the house, but she reveals that she shared much more than that…

At first, Sara didn’t realise what she’d done. The house itself had become self-aware, but it was seeing everything as if it was through Sara’s own eyes. The house saw her own image - or rather Sara’s image - standing in the kitchen with her hand still in the indentation, and without even asking, she knew what Sara had wished for. The Doctor was released from his glass prison, and he collapsed to the floor, coughing and wheezing. Steven gave him an arm for support, then the two of them sat at the coffee bar while Sara told them what she’d done. After listening to her explanation, the house disposed of Richard and Alex’s bodies and found them plots within her own foundations. She didn’t know anything about their burial rituals, but she wanted to be respectful. In the end, she dug deep into Sara’s mind and recited the oath of the Space Security Service. She promised to make things better, to make things right and to protect and serve.

Robert asks Miss Kingdom when this story happened, but she tells him she stopped counting after the first thousand years. The seasons may have changed, but she still draws her power from the Sun and the stars. The young man looks around and says the guest house isn’t anything like the dream house she described, but she tells him it’s warped with age and changed with the wishes of those who’ve stayed here. He asks her who built her as he’s not familiar with a science that can grant people’s wishes, but Miss Kingdom responds with another question - were any other similar houses built back then and how many of them are still standing? She wonders if that’s what ended their civilisation and left the world like it is now. She doesn’t have any of the answers and she doesn’t even know how long the house was standing before the Doctor arrived.

Robert tells her she’s not Sara Kingdom and, in fact, she’s not even a real person, but the house says she’s all that’s left of her. The original Sara soon left with the Doctor and Steven, and although the house wanted them to stay longer, it was no more than she deserved after what she did to them. She’d looked into Sara’s mind and discovered things about Sara that she didn’t even know herself. She hopes Sara found what she wished for and she sometimes imagines what she might be doing right, although she realises they’re probably all be dead by now. The young man regards the house as Sara’s ghost and she agrees that there’s some truth in that.

She now realises this is why Robert is here. She didn’t want to read his mind as she doesn’t like to pry uninvited, but she knows that he’s an officer of the law, that he crossed the Fens in terrible weather to have a chat with her, that he’s wary of her every hospitality and that he seems uncomfortable talking to the air. He asks her if she’s able to make herself corporeal and when she asks if it would help her case if she did, he admits he was just being curious. The house says she wants nothing for herself and she just wishes to take care of her guests. The man says he’s heard different stories - from people who’ve been picked up and ejected through the door - and the house tells him she uses her judgement, as any landlady would. It must be these misbehaving people who’ve concocted the wildest stories about the house, claiming it’s haunted. Robert says the law requires him to exorcise her, but the house has heard this before from his predecessors. They all listened to her story, they all ate her broth and each of them agreed to make an exception in her case, even the ones who lived in less enlightened and more credulous times. Robert refuses to make an exception and she suspects it's because the scientist in him doesn’t like the superstition in the law. But the house swore to uphold the law, and even now after all this time, she promises to abide by whatever the young man chooses. She says she can let go of herself and disperse into the air if that’s what he wants.