As half of The League of Gentlemen and the creators of Psychoville, writer-performers Reece Shearsmith and Steve Pemberton are known for their expertise in combining comedy, drama and horror – and their latest venture is no exception. Anthology show Inside No. 9, which has so far run for four series on BBC Two since 2014, has built a reputation for managing to make its audience laugh, gasp and shudder in equal measure.

Certain episodes of Inside No. 9 have settings that place them firmly within the horror genre; a gothic mansion, a séance, a secluded cabin in the woods, an art gallery after dark… However, other episodes that are set in more everyday locations, and revolve around domestic themes such as marriage and family, have proven themselves capable of being just as chilling and disturbing.

After taking us inside the grand country mansion of ‘Sardines’ and the stylish modern house of ‘A Quiet Night In’, the third episode of Inside No. 9’s first series has a setting that, for most viewers, will be more familiar – a small city flat above a corner shop. ‘Tom & Gerri’ is about schoolteacher and aspiring writer Tom (Reece Shearsmith) whose life is turned upside down when he welcomes a homeless man into his flat.

The gradual invasion of Migg (Steve Pemberton) begins with him returning Tom’s lost wallet, for which he is given a cash reward, and then going back to the flat with a thank you gift, which results in Tom politely inviting him inside for a quick drink. Tom can barely hide his discomfort with Migg’s presence, visibly wincing as he starts to remove a shoe, revealing a truly disgusting foot. He notices Tom’s concerned expression when he sits down on the sofa and offers to get back up, but Tom sighs “you’ve done it now, best to just… contain it”. We get the impression that Tom is going to bin everything in the flat that Migg has touched once he has left.

Migg doesn’t leave though, because the two men begin to get on and become increasingly drunk, leading to Migg staying the night and helping himself to a bath the next morning. He invites Tom to use the bath after him, but Tom politely declines when he gets a look at the state of it.

In addition to Migg being physically repulsive, it soon emerges that he is also a corrupting influence. At the beginning of the episode, our first glimpse of Migg is a picture drawn by Tom in which he appears to have devil horns, and this provides a hint of what is to come. After his first night in Tom’s flat, Migg easily persuades Tom to skip work and call in sick, and it isn’t long before he is hiding Tom’s mobile phone, stealing his post and sneakily deleting messages from the landline answering machine.

Once Tom quits his teaching job and starts signing on, Migg promises to collect his benefits for him, but as the wait goes on and on, it becomes clear to us that Migg has in fact kept the money for himself. The situation eventually reaches a point where Migg is clean-shaven with new clothes and a job, while Tom is bearded, dishevelled and living in squalor. Highlighting their role reversal is a scene which sees Tom cowering on the floor, whimpering “this is too much” as Migg hands him some cash.

The way in which Tom has his home invaded and his life taken over might be disturbing enough, but adding a further dimension to the story is the possibility that Migg isn’t real. This seed is subtly planted early on, when Tom asks his girlfriend Gerri (Gemma Arterton) if she can see “the tramp” outside and Gerri responds “I can’t see anything”. Throughout the episode, we never see Gerri and Migg in the same room at the same time, with one often arriving just moments after the other has left. Similarly, when Tom’s friend/colleague Stevie (Conleth Hill) pays a visit to the flat, Migg is nowhere to be seen and Stevie even nicknames him “mystic Migg”.

As a result of these hints, the viewer is led to suspect that Migg is just a figment of Tom’s imagination. Gerri eventually appears to confirm this theory by insisting to Tom that “there is no Migg” and that he must be having some sort of nervous breakdown. She commands him to “get this Migg out of your head once and for all”. In the subsequent scene, the flat is clean again and so is Tom, leading us to believe that he has purged Migg from his mind and got his life back on track. However, there is another revelation still to come – that Migg was real along and it is in fact Gerri, who died in a car accident, that Tom has been imagining.

During the last few minutes of the episode, horror dawns on Stevie’s face as he hears Tom say “Gerri’s just putting the kettle on” and then discovers a drowned Migg in the bath. This ending is made all the more disturbing by Tom’s inability to understand what he has done, calmly assuring Stevie “oh that’s just Migg… he’s not real”, and by the final chilling shot of Migg’s lifeless body in the bath.

An equally unsettling domestic horror story is told in the second installment of Inside No. 9’s second series, ‘The 12 Days of Christine’. This episode, which is frequently hailed as the show’s most affecting, navigates us through twelve significant days in the life of Christine (Sheridan Smith). We follow her as she meets Adam (Tom Riley), who soon becomes her boyfriend and then her husband and the father of her child. In the latter days that we see, however, the couple are no longer together and Christine is struggling to cope with life as a single mum, while also grieving the death of her father.

So far so normal, but ‘The 12 Days of Christine’ is more than just a whistle-stop tour through a woman’s adult life. The first sign that something might be amiss appears during day two, which is Christine’s first Valentine’s Day with Adam. She receives a card in the post from an ex-boyfriend and seems troubled by the thought that he knows her address. Things get stranger still on Mother’s Day, as her mum mentions that the ex in question died when he was just a teenager, but Christine has no recollection of this. We are left wondering if this mysterious ex could be alive and stalking her, or even if his ghost could be haunting her…

For a while, signs appear to be pointing towards the supernatural theory. In one particularly eerie sequence, Christine gets pelted with eggs by an unseen assailant and walks into her kitchen to find that there are broken eggs all over the floor. After approaching a cupboard with a shuddering door, she suddenly turns around to be faced with a man (Reece Shearsmith) standing in the middle of her kitchen, wearing a soaking anorak and steamed up glasses. Once Christine’s son is born, she has visions of this mysterious man trying to steal him away from her. She hears his voice through the baby monitor saying “come on little man, let’s get you out of there” and, on another day, she enters her son’s room to find the man desperately clutching him. Other allusions to the supernatural include Christine’s housemate being nicknamed “The Grudge” and Christine’s deceased father giving her advice from beyond the grave.

Another possibility seems to be that, rather than something supernatural going on, Christine is suffering from a condition which is causing her mind to deteriorate. In addition to having no memory of the death of her ex-boyfriend, Christine shows signs of losing her mind when she panics over her son burning his hand on a sparkler, only to discover that he is completely fine and there is no burn mark at all. Her mum suggests that she must be getting confused because she burnt her hand on a sparkler when she was his age, causing Christine to despair “I’m getting everything jumbled up”.

Throughout the episode, we have been able to hear a heartbeat and a beeping sound between each transition of time. In the final day that we witness, it emerges that these recurring noises – as well as a shot in which Christine accidentally knocks a toy car over with her foot – were subtle clues. As Christine sits at a table with Adam, her parents and her former housemate, with no idea why they are all there, and is presented with a photo album full of memories, she ponders “this is like my whole life is flashing…”

There is no need to finish the sentence; after a few seconds of silence she states “I think I know what this is now” and the viewer is in the same position. As the episode reaches its conclusion, we see Christine slumped across her steering wheel in the aftermath of a car accident, and all of the clues suddenly fall into place. It is raining heavily, the familiar beeping sound is coming from the car, a damaged pack of eggs lies on a seat, and the song Time To Say Goodbye (which we have heard several times throughout the episode) is playing on the radio.

It becomes clear that the anorak-wearing man who has been invading Christine’s memories was the cause of the accident, as he crossed the road without looking, and he has thankfully managed to get her son out of the vehicle. Christine’s memory world allows her to say one last goodbye to her family as she slips away. Having spent the last half-hour getting to know Christine, the viewer almost feels included in this farewell and is likely to be shaken by the final shot of her staring directly into the camera.

Similar to ‘The 12 Days of Christine’, the fifth episode of Inside No. 9’s third series, ‘Diddle Diddle Dumpling’, makes good use of subtle hints pointing towards a tragic conclusion. This episode revolves around the unravelling of David (Reece Shearsmith), who becomes obsessed with a shoe that he finds outside his house.

David lives with his wife Louise and their young daughter. He is a stay-at-home dad, and when Louise (Keeley Hawes) goes to work, we see him spending the day doing housework with a rather bored expression on his face. This lack of excitement in his everyday life, combined with the cold, clinical aesthetic of the family’s house, makes it believable that David would become intrigued by the mysterious shoe and set out to learn the story behind it.

On the day that David finds the shoe and first brings it into the house, he stares at it while tuning out what Louise is saying at the dinner table. This provides our first hint that the shoe is going to be a disruptive influence in their lives. It isn’t long before David is creating posters of the shoe, in an attempt to find out where it came from, and plastering them all over the area. Louise’s complaints about the advertisement of their phone number fall on deaf ears, and when she is on the phone, David tells her to be quick because “people might be trying to get through”. In addition to these delusions, he also becomes increasingly possessive of the shoe, scolding his daughter for playing with it and refusing to let his wife touch it.

Moving forward from spring to summer, the shoe-based tension between the couple reaches boiling point when their mutual friend Chris (Steve Pemberton) comes round to the house and Louise tells David that she has thrown the shoe away. In a reference to the horror film Magic, about a ventriloquist obsessed with his dummy, she challenges David to go two minutes without mentioning the shoe. Of course he can’t, and before the time is up he is demanding to know “which bin is it in?” and rifling through them until he is reunited with it. He tells Chris: “I’m not going mad. A pair of shoes, they deserve to be together… have to be. It’s how they belong.” This intensity suggests that his fixation on the shoe is being driven by something more than just boredom.

As David’s attempts to solve the mystery become more extreme, talking about his ‘mission’ on the radio and creating a website for the shoe, someone claiming to be the owner comes forward. After putting Ted (Mathew Baynton) through a series of tests to determine whether he is really the owner, such as asking him to identify “the correct tread” from various photos, David is visibly reluctant to part with the shoe. The very ordinary story of how Ted lost it clearly isn’t exciting enough for him, and he confesses “I’m finding this really hard” while choking back tears as he hands it over. Although he remarks “that’s that done now, mission accomplished”, we get the sense that his obsession is far from over.

The story then jumps from summer to autumn, and the fact that David is wearing a suit and has a job implies that things have improved now that the shoe is gone. However, when his daughter tells him her lines for school assembly, which include the words “one shoe off and one shoe on”, something in his expression slips…

Finally, manic classical music takes us into winter, by which time David’s obsession has returned in full force. He has discovered that Ted was in fact hired by Louise to collect the shoe, because she was so desperate to have it out of their lives, and his distress causes Louise to confirm something that we’ve come to suspect: “It’s not about the shoe is it? It was never about the shoe…” We finally learn the tragic root of David’s unhinged behaviour – that their daughter originally had a twin brother, who died six years ago, and David has never fully been able to get over it. Just like the separated pair of shoes, his twin children are “two halves and one of them’s gone”.

Over the course of ‘Diddle Diddle Dumpling’, a recurring visual theme of symmetrical pairs, i.e. twins, has alluded to the episode’s big reveal. From the number of the house being 22 (the ‘No. 9’ in this instance was the shoe size) to shots of David between two chairs, two lamps, two glasses and so on, the idea that things come in pairs has had a subtle presence throughout. Particularly eagle-eyed viewers may notice that the brass hare, which can be spotted in every episode, even has its own twin here. A few clues have also been scattered in the dialogue, such as David briefly referring to the shoe as “he” while talking to Ted.

As is often the case with Inside No. 9, there turns out to be more than just one chilling twist in the tale. After we learn the truth behind David’s fixation on the shoe, it emerges that he has paid a visit to Ted and retrieved his precious shoe by force, with blood on his hands suggesting that he has possibly murdered him. We ultimately discover, via a close-up of a photo and CCTV footage playing during the episode’s credits, that David is in fact the owner of the shoe and it was him who put it outside the house to begin with.

‘To Have and To Hold’, the fourth installment of Inside No. 9’s fourth series, is another episode with themes of domestic troubles and marital discord running throughout. At the centre of this story is Harriet (Nicola Walker), who wants to spice things up in her marriage, but husband Adrian (Steve Pemberton) is being unresponsive to her efforts.

From the very beginning of the episode, Adrian is painted as an unexciting man. We first see him doing a jigsaw at the kitchen table, wearing glasses on a string, and he barely looks up when his wife arrives home. Harriet reads him the vows that she has written for their planned renewal ceremony, but when Adrian shares his, they have clearly been taken straight from an official website. Making matters even harder for Harriet is the fact that her unromantic husband is a wedding photographer, and she laments “you spend all that time downstairs working on other people’s wedding photos…”

During a scene in Adrian’s darkroom downstairs, other reasons for their relationship issues emerge. Adrian mentions that they don’t have children, blaming his “weak sperm”, and Harriet brings up money problems. As she suggests that she could go back to work, the atmosphere suddenly becomes more tense. To reflect this, more lights are switched off, causing the darkroom to become even redder than before. We learn that not only did Harriet leave work after cheating on her husband with a colleague, but also that Adrian has seen them together recently. However, Harriet maintains that they were simply talking about her returning to work and shifts the blame back to her husband by telling him “I love you, but you won’t let me in”.

In addition to the previously mentioned renewal ceremony, Harriet tries to spice up the marriage one night by dressing as a nurse and instigating some roleplay. Adrian is clearly not enjoying himself though, and thankfully for him, the ‘romantic evening’ is interrupted by a couple who have come round to see their wedding photos. Harriet is furious and sarcastically tells the couple “I work in a mortuary, I handle corpses” referring to Adrian’s unenthusiastic response to her seduction attempts.

At one point during ‘To Have and To Hold’, we hear Harriet ask her husband in exasperation “what do you like, Adrian?” and eventually we do find out… After an argument with his wife, Adrian goes down to his darkroom and removes a board of photos to reveal a door. Inside the hidden room is a prisoner, whom we ultimately discover is the couple’s former cleaner. Adrian has kept her in there for around nine years and fathered a child with her in that time. Even more disturbingly, the child is called Levi, which Adrian earlier said would have been the name of his and Harriet’s son if they’d had one. Suddenly his aversion to intimacy with his wife makes sense, as does the way in which he quickly shot down Harriet’s suggestion that they could move house.

Harriet eventually discovers the hidden room, after she surprises Adrian by booking a holiday and he throws himself down the stairs in the hope of injuring himself and avoiding it. Shaken by the fact that she has been married to a man with a horrifying secret and never suspected a thing, she states “I thought I was living with the most boring man in the world… turns out he was a monster”. We get the impression that Adrian has died as a result of his fall, only for the last few seconds of the episode to reveal otherwise. As we learn that Adrian is now imprisoned in the hidden room, Harriet explains: “He’s my husband… to have and to hold, from this day forward, for better for worse, for richer for poorer, in sickness and in health, to love and to cherish, til death do us part”.

While certain episodes of Inside No. 9 are easily identifiable as horror stories from the offset, such as ‘Private View’ which begins with a murder, others are not but then become more macabre as they progress. Sometimes these episodes in the latter category are the ones that prove to be the most disturbing, as their familiar domestic settings and seemingly ‘ordinary’ characters make the chilling moments all the more surprising.