In the kitchen of 13 Bannerman Road, Luke sits and reads an e-mail from Maria whilst Sarah readies his lunch, voicing her distress over the latest child abduction in the area. Noticing that her son is clearly upset by his friend’s recent departure, she tries to comfort him, claiming that he will see Maria again soon – not least because her mother is planning to get married again.

Clyde arrives and tells them a new family is moving into Maria’s old house. Sarah makes the two boys swear not to mention their secret life to the new neighbours, and they agree. However, Clyde rouses her suspicions when he notes that Maria may have left some alien artefacts in the house by mistake.

At school, Luke and Clyde are talking about Maria when they are met by a new girl named Rani, who reveals her family to be the one moving in over the road from Luke. As the three students prepare to go to class, Rani catches a glimpse of something in the corner of her eye – a shape that looks suspiciously like a clown.

Sitting in class, Luke and Clyde are introduced to their new headmaster – Mrs Chandra – who introduces himself in a somewhat icy manner. Whilst he addresses the class, Rani glances out of the window and glimpses the clown again; now standing outside, but it disappears in the split second her attention is drawn away from it. Mr Chandra, meanwhile, warns his pupils to be on the lookout for anything suspicious, and to look after themselves following the recent disappearances.

Back on Bannerman Road, Sarah goes to visit her new neighbours. She is greeted by a kindly woman named Gita, who welcomes her inside. Whilst Gita searches for some cups for the tea Sarah has brought her, Sarah does a quick scan for any alien technology that may have been left behind, but finds the house is clear of such items.

In the school playground, Rani and Luke talk about Maria, and Luke again confesses his sadness at his friend having left. Rani then voices her concerns about the recent disappearances and confesses she has a taste for the unusual. She asks Luke if he has seen any odd goings-on around the school, but before he can answer he is distracted by Clyde, who accidentally hits Mr Chandra, who is touring the playground, with a ball. The new headmaster turns on him and orders him to go to his office.

Back on Bannerman Road, Sarah talks to Gita about her job as a journalist, and Gita reveals her daughter Rani is interested in journalism. She proposes Sarah might be able to give her a few tips, but Sarah insists her work is somewhat specialist.

As Clyde awaits a scolding from Mr Chandra, he jokes with one of his friends, Dave, who leaves to fetch some supplies for art club from a store cupboard. Clyde walks around the corridor, casually glancing in a trophy cabinet when he sees the reflection of a clown staring back at him. He turns to look for the jester but all that is to be seen is the closing door of the store cupboard. He steps inside to find his Dave is nowhere to be seen, all that remains is a pile of pencils and paper that have been dropped on the floor.

He hurries back into the corridor, where he sees the clown, who is holding a red balloon, standing in the distance. He tries to chase after it but it disappears, vanishing from view with one wave of a colourful cape. Clyde searches the toilets for any sign of the clown, and finds it waiting for him, residing inside one of the mirrors. Clyde asks what he wants and the clown claims he wishes to offer Clyde a balloon. Extending his arm out of the mirror, the clown offers him the inflatable, but before Clyde can take it Mr Chandra arrives and the clown disappears. Going into Mr Chandra’s office, Clyde tries to explain about the clown, claiming it has taken his friend. Mr Chandra is sceptical, theorising that Dave has probably left school early.

After school Clyde tries to tell Luke about the clown, but his friend is also somewhat disbelieving, not being able to understand why anyone, even aliens, would want to dress up as a clown to snatch children. Once again Clyde sees the clown standing in the distance, and tries to show it to Luke, but it disappears again before Luke can follow his friend’s gaze. Clyde hurries off in the direction of the clown and Luke follows. A chase ensues through the streets; but neither of them is able to track the mysterious figure down.

Eventually they come across a red balloon, identical to the one held by the clown, and Clyde reaches out to grab it when Rani appears and tells him not to. Following her warning the balloon bursts. Walking back to Bannerman Road, Rani confesses that she too has seen the clown, but remained silent because she thought nobody would believe her. Clyde urges her to ignore the clown but Rani is insistent the matter must be investigated. Before they can talk about it further, Mr Chandra appears, and Rani reveals he is, in fact, her father. Sarah and Gita also arrive and Rani enthuses about learning journalism skills from Sarah, who is still somewhat reluctant.

Going up to the attic, Sarah admits they need to investigate the disappearing clown, and Luke agrees to keep an eye on Rani, whom they fear may be in danger.

Across the road, Rani looks through some of Dave’s school books, which her father has brought home and is planning to hand over to the police in case they could be of use in finding him. She finds many of them covered in drawings – specifically pictures of the clown she and Clyde have seen. She looks up from the book to see the clown standing outside, before jumping at the speed of light to stand inside her house. However, when Gita arrives it disappears again.

Sarah and Clyde talk to another of Dave’s school friends, a boy named Steve, and ask if he knew of any connection between the missing boy and clowns. Steve recalls that both he and Dave encountered a clown handing out tickets at the local tube station – tickets both Dave and Tony, the boy from the park, accepted.

Suddenly Clyde recalls that he also has one of the tickets – presented to him by his mother – and produces it from his pocket. It is an admission ticket for ‘Spellman’s Magical Museum of the Circus’.

Sitting in Rani’s room, Luke listens as his new friend theorises that the clown is somehow getting closer to her, and that it may have something to do with the supernatural. Luke, recalling his earlier promise to his mum, tries to deter this train of thought, but Rani is insistent. Looking through one of Dave’s sketchbooks they find more pictures of clowns – and a ticket for Spellman’s Museum. Rani suddenly remembers that she too has a ticket, collected from a vendor at the station. Remembering that Luke still cannot recognise the clown, Rani realises that only children who have been presented with a ticket can see it.

Sarah and Clyde go to Spellman’s Museum, where Sarah admits that clowns make her skin crawl. They step inside and are greeted by Mr Elijah Spellman himself, a circus ringmaster. After Sarah addresses the issue of clowns, Spellman recounts that throughout history fools and jesters have been required to make people laugh. Sarah tells him there is something far darker to them, something children can sense.

Luke and Rani soon arrive at the museum and make their way inside, where, unbeknownst to them, Clyde has found a painting of a man wearing the same colours as the clown he an Rani saw. Mr Spellman explains that the man is the Pied Piper; the colours he wears – red, blue and yellow – signify that he was in fact a travelling entertainer. Sarah makes the connection between the Pied Piper and the clown seen by her young friend – both snatch children. Clyde protests that the Pied Piper is just a myth, but Sarah warns him that legends can have their seeds sown in reality.

Suddenly Mr Spellman vanishes, and Sarah tells Clyde it is time they left. They turn to go when Luke and Rani enter. Before they can talk further, the clown exhibits, normally inanimate, spring to life and begin chasing them. Sarah claims that they must be controlled by Spellman, animated by telekinesis. Fascinated, Rani asks who Spellman really is and how he holds such a power; and Luke confesses he is probably some sort of alien.

Turning a corner, the group find themselves trapped between two scores of animated clown dummies. Sarah uses her Sonic Lipstick to make several of them seize up, allowing them to escape. Rani, astonished by Luke’s revelation, turns to Clyde, who tells her that one alien alone can be more dangerous than a whole battle fleet.

Finding the doors sealed with telekinesis, therefore unaffected by the Sonic Lipstick, Sarah is forced to find another way out. However, as she turns to walk back into the museum she is confronted by Mr Spellman, who appears out of nowhere, and claims that they are all trapped. Sarah demands to know who Mr Spellman really is and what he wants. Immediately he transforms into the man Clyde saw in the painting.

“I am the Pied Piper, who conjured away a whole town’s infants, and has chilled the hearts of parents, for more than seven centuries…”

Again his appearance changes – this time to the clown that has been taking the local children.

Sarah grabs a fire extinguisher and unsuccessfully tries to freeze Odd Bob with it. Whilst Luke and Clyde force the doors, Odd Bob turns on first Rani and then Sarah Jane, claiming that of all the beings she has fought, there is only one thing that she is truly afraid of – the painted face of a clown.

Rani’s mobile phone rings, unwittingly saving the day by freezing Odd Bob and breaking the seal covering the doors. The group escape back to the car and speed away, aware that Odd Bob will not be frozen for long. Upon returning to Bannerman Road Sarah unwillingly allows Rani entrance to the attic, after first offering her the chance to return home and forget what has happened.

Sarah explains the undercover life she, Luke and Clyde now lead – seeking out alien life and averting worldwide disaster. She then presents Mr Smith, and asks him to provide background information about the Pied Piper and Odd Bob the clown. He tells them that in the 1930s a spate of children went missing in America, and that the disappearances were traced to Odd Bob. He then recalls the events of the town of Hamlin – and claims them to be historically true – the Pied Piper was real.

Following a scan of the ticket Rani was given, Mr Smith connects it to a meteor that landed on Earth in 1283 in Saxony – the year before the Piper arrived. He requests Sarah get him a fragment of the meteor for analysis, and directs her to the Pharos Institute, where the rock is currently being held.

That night Sarah walks Rani home, and tells her she cannot accompany her to get the meteor sample as she does not want another child to look after; Sarah confesses that if she had her time again, she would even exclude Luke and Clyde from her dealings with aliens so as to ensure they were safe.

However, to protect Rani from any attack from Spellman, Sarah gives her an alien defence shield – a small metallic device that will emit a force field around her bedroom to stop anyone entering. Sarah makes Rani swear to secrecy about all she has seen and then wishes her goodnight.

Some time later, Luke finds his mother sitting alone downstairs looking at pictures of clowns on her laptop. He asks why she is so scared of them and she tells him about her childhood – one of her most vivid memories is that of a marionette puppet hung in her room that scared her as she felt it was always looking at her. The fear of it was the only thing to make her call out for her parents – who died when she was a baby. The night her fear really began was during a thunderstorm, when she thought the puppet had come to life.

The next morning, across the road, Rani’s mother Gita enters her daughter’s room with a cup of tea and is knocked back by the force field. Rani disarms it and convinces her mother it is just a migraine before ushering her out and drawing back the curtains – only to find a red balloon floating in the garden.

Sarah arrives at the Pharos Institute and is welcomed by Professor Rivers, who thanks her for her help in covering up the recent controversy surrounding Nathan Goss and the MITRE experiments. As a return she allows her access to the meteor, which Sarah takes a sample of using her Sonic Lipstick whilst the Professor leaves the room.

Suddenly Spellman appears, then transforms into Odd Bob, who taunts Sarah by claiming that she will never be able to understand him, and unnerves her further by showing knowledge of her nightmare as a child, which, he alludes, may really have been a reality. Sarah refuses to be frightened, realising it is fear Spellman (whom Odd Bob has morphed into) uses as a weapon. Spellman claims he will soon chill the blood of a nation. Before he can reveal how, Professor Rivers returns and Spellman disappears.

At Park Vale School, the children in the playground watch as a fleet of red balloons descend upon them. As they grab them, they come under the control of Spellman, and begin exiting the school. Unaffected, Luke, Clyde and Rani follow them.

In the attic, Sarah listens as Mr Smith reveals that Spellman is a living entity formed from pure emotion – in this case fear. The entity travelled to Earth as a meteor, and upon landing required more fear in order to survive – hence the disappearance of the children in Hamlin. The Piper / Spellman / Odd Bob have been abducting children ever since as a way of feeding.

Sarah receives a phone call from Luke. He tells her about the children from school, who are now heading towards the museum – this is Spellman’s threat. Sarah turns to Mr Smith: “I have a job for you”.

She then hurries to the museum, where Spellman welcomes the children and ushers them inside. Sarah confronts him and unveils her plan – Mr Smith has accessed the phone numbers of every child. He calls them all simultaneously, the signal in the phones breaking the bond holding them and allowing them to return. Turning on her, Spellman tells Sarah he will make her experience a much worse fear, and makes Luke disappear.

Sarah hurries inside the museum, locking Clyde and Rani outside to keep them safe. She then tries to find Spellman, and follows an echoing sound into the hall of mirrors, where Luke appears trapped inside. Odd Bob also begins haunting her, but she puts an end to the phantasmagoria by blasting the mirrors with her Sonic Lipstick – revealing a hidden doorway.

Outside, Rani and Clyde find another way into the building – an open window – and hurry to help their friend. Sarah continues her search for Spellman, and is confronted by Odd Bob, who continues to taunt her. He explains that Luke has been sent into a void between this world and another – where all of the children he has abducted are kept before they eventually disappear completely. Sarah orders him to bring them back but he refuses – it would defuse the fear that surrounds him.

Reverting to the form of Spellman, he claims that nobody can defeat him for fear is invincible. However, Rani and Clyde have already formulated a plan. Clyde confronts Spellman and begins making jokes, ignoring his threats to abduct him as well. Rani joins in, and Spellman begins to appear unnerved. Laughing starts echoing around the museum – the one thing that can defeat him.

Sarah and Rani then discover the meteor fragment is glowing – pulling Spellman back inside after centuries of being able to resist it. As his identity begins to falter, Spellman disappears, and immediately Luke is returned – much to Sarah’s jubilance.

Back in the attic, Sarah stows the meteor fragment away as Mr Smith explains to the others that all the recently-abducted children have been returned home with no memory of what has happened to them.

Stepping outside, Rani asks Sarah what she should do now. She tells her to keep her new life secret, in order to protect it. Soon her parents Gita and Haresh arrive, demanding to know where she has been. She claims she, Luke and Clyde were researching for a school project, and that they had nothing to do with the temporary disappearance of the rest of the students.