Ghost Walk was the two hundred and thirty-fifth story in Big Finish's monthly range. It was written by James Goss and featured Peter Davison as the Fifth Doctor, Matthew Waterhouse as Adric, Sarah Sutton as Nyssa and Janet Fielding as Tegan Jovanka.
This is a city of ghosts and no-one knows them better than Leanne. Twice a night she leads tourists to visit the most haunted sites - the Hanging Yard, the Witch Pool, the Screaming House, and, of course, the Catacombs.
Leanne’s realised the ghosts of the city are real. Something’s lurking in the Catacombs - an ancient force that has been growing in the darkness for centuries. Sabaoth is returning and they must be stopped before they devour the world. Leanne knows this, because a ghost told her.
A ghost called The Doctor.
Leanne leads a guided tour of the Catacombs. Initially successful, things spiral out of control when they hear strange sounds, and other frightening events begin to occur... when suddenly, Leanna hears the voice of the Doctor in her head.
The TARDIS crew land in the 17th century searching to help the senders of a distress call they intercepted. They split up and Adric and Nyssa are attacked by something unseen. Tegan and the Doctor discover a wall with blood markings on it and a pile of bones that shown sign of damage at the deepest molecular level. Adric, having fallen down the stairs in a panic, hears Nyssa call to him that she can't move as the creature seems to be holding on to her and instilling fear in her against her will. Adric tries to save her but also becomes stuck when the creature holds on to him. Tegan and the Doctor find the two frozen on the floor shivering, and prop them up, and they explain that the alien subdued them to lead the Doctor to it. They hear the creature's roar and run back to the TARDIS. Once inside, they realize the TARDIS is dead, and was trying to leave which is why it was making groaning noises before when they first arrived. The Doctor explains he can get it working again but they need to go back outside. They get a displacement generator working and he transports Nyssa, Tegan and Adric elsewhere. Just as he prepares to take on the creature, it is revealed Tegan didn't listen and left the circle for the generator at the last second to stay and help the Doctor, suspecting he didn't actually have a plan. He admits she's right. Leanna asks the Doctor if this is how he got stuck here, which he admits it is, but when she asks how he got out he reveals he never did and that he died here...
Nyssa lands in a village and the townsfolk are convinced she's a witch and attempt to burn her, however, she is saved by Matthew Doyle the Reverend who takes her on horseback back to the vicarage. The Doctor and Tegan theorise how the creature managed to feed on the TARDIS, and the Doctor tries to help Tegan regain composure after she becomes tired, where the Doctor realizes the creature is feeding on her. He gets her to safety.
Adric, having landed in the same village at a different point in time, is put on trial for stealing some bread but this is interrupted when he spots someone wearing a cloak, revealed to be a member of the Brotherhood of Sabaoth. Matthew and Nyssa have a chat where she also learns about the Brotherhood of Sabaot and she learns she has been moved forward in time but not space and they plan to have Matthew go and visit their temple to see if there's anything they can learn. Tegan and the Doctor discuss about what they will do now and how they will escape. They learn that the creature's name is Sabaoth. Matthew returns having been unsuccessful in talking with the brotherhood, and being egged by children. The more time she and Matthew spend together, more rumours, spread by Mrs. Stubbs, the Reverend's housekeeper at the vicarage, fly around the village that the Reverend has been bewitched by her. Matthew eventually reveals he has fallen in love with Nyssa but she turns down his advances due to the situation. Adric finds some people, having fled the trial, and asks them to tell the Doctor he's here, however, they are confused as they know no one of that name. Just then they are interrupted by cloaked men of the brotherhood and Adric tries talking to the cloaked men on behalf of the frightened villagers, while the events are recorded by a "journalist" on the scene while Adric is taken to his execution, his fate decided.
Nyssa and Reverend Matthew arrive at the church where he is to give a sermon, however, the villagers block him from entering until he recants and rids himself of Nyssa. Matthew attempts to defend her and her actions but the villagers are unconvinced and attempt to burn her. Matthew, in a change of heart, sides with the villagers (having had his heart broken by Nyssa) and they attempt to drown her in a river as the Brotherhood of Sabaoth encroach on her position. Meanwhile, Adric is placed in the gallows to be hanged, and the floor beneath him is dropped...
Leanne in the present explains that a boy named Derrick was hung from the gallows but mysteriously disappeared during the hanging and takes out a newspaper article and picture to show it, which the Doctor, in Leanne's head, tries to get her to give him a good look. They get into an argument and she tries to ignore him. He tries to convince her to explore the catacombs she gave a tour at earlier but instead continues her tour to show the "The Witch of the Lake". Meanwhile the Doctor and Tegan, in the past, continue to try and figure out what to do. Tegan, realizing a pickaxe would be helpful for a plan she has to tunnel out, goes looking for one inside the TARDIS but Sabaoth, projecting itself through the consumed TARDIS conscious, traps her inside the TARDIS and the Doctor tries to get inside but gets locked out. Tegan and the creature talk and it flings her mind forward in time as it drains her energy.
The Doctor managed to get inside the TARDIS and finds Tegan collapsed on the floor and he finally confronts Sabaoth. In the present, he guides Leanne through the catacombs where they find his tomb, where his body is buried. However, he stops Leanne from breaking it open, explaining that currently he's both dead and alive, like a Schrodinger's ghost, as they neither know whether he is actually dead or alive (he's supposedly dead, but she can still hear his voice so he might be alive and neither believes in ghosts) and that observing the body of him actually being dead will create a fixed point in time, ensuring his death. The Doctor hopes to find a way to avoid this but Leanne is still considering breaking in if it means she will be rid of the voice in her head.
Tegan slowly reawakens and explains to the Doctor she went to the future and tried to warn them but is not sure it worked. The last of her energy drains away and the two share a heart-felt moment before she passes on. The Doctor explains in the present to Leanne that he realizes now he's here to save her and they hear a voice calling from around them. The Brotherhood of Sabaoth surrounds them and encroaches on them, however, he tries to calm her down explaining that they're not real in the ordinary sense and are more like smoke and mirrors/illusions projected by Sabaoth and Leanne makes a run for it.
Some time ago, a boy and his girlfriend Katya play a game with a Ouija board and Katya becomes possessed, warning them that "Sabaoth is coming".
In the past the Doctor berates Sabaoth for killing Tegan and prepares to suffer his fate. Sabaoth continues to taunt the Doctor and slowly drain his energy while he continues walking around and staying active to not succumb to sleep and have the rest of his energy swiped by Sabaoth. The two continue to talk as the Doctor walks through the dead TARDIS and Sabaoth explains he plans to keep feeding on everything else by bringing himself into the universe from his spectral form.
In the present Leanne continues to run from the illusory cloaked men and the Doctor explains that she has traversed so much of the sites and crossed the many psychic barriers that Sabaoth is using her as an anchor. Meanwhile Katya is brought to an expert exorcist by her boyfriend and the exorcist lulls her into a trance where she attempts to warn them that they must not let Sabaoth free. She cries that they must find the Doctor while the expert attempts to perform an exorcism, when suddenly the voice inhabiting Katya cries that they need to listen to her and that they don't understand as her name is Tegan Jovanka...
Leanne awakens the next morning to find that she has managed to escape the Brotherhood but the Doctor explains that she was supposed to and explains that Sabaoth planted a trigger in her mind and that going back into the catacombs will be catastrophic, however, she berates him, explaining she needs to pay her rent even if the world will end because of it (as he explained) and will be going back again to give a tour tonight. In the past, the Doctor builds a wall around himself and the dead TARDIS as he dies, explaining to Sabaoth that he cannot allow people to get their hands on the body of a dead Timelord. Leanne has lunch in a cafe and when she refuses to follow the Doctor's advice he begins to cause things in the cafe to shatter, break or rumble. Overwhelmed, Leanne tries to shut him down and accidentally manifests telekinetic powers, blowing out the city's electricity supply but at the very least she can no longer hear the voice of the Doctor in her head.
Later, Leanne gives a tour of the catacombs but begins hearing whispers and voices that she cannot block out. She explains that in the residence built on top of them, two students playing with a Ouija board in one apartment lead them to rediscover the catacombs running underneath the entire street (Katya and her boyfriend). She then leads them to the Temple of Sabaoth, and her patrons are revealed to be the Brotherhood of Sabaoth. As she prepares for her fate, the Doctor reveals himself just as Sabaoth appears.
The Doctor reveals he escaped death by going into a healing coma (an ability of Timelords) after he had sealed himself inside and projected himself into the head of the person that Sabaoth was using to be bring himself back into the world, Leanne. The Doctor and Leanne face Sabaoth together.
The Doctor awakens to discover himself in a fully operational and energized TARDIS which he used to go back and save Nyssa from being drowned and Adric from being hanged, as it turns out Leanne's telekinetic outburst was channeling Sabaoth's power and managed to send him back in time and restore some power to the TARDIS, allowing him to go save the others. In the present the Doctor, Nyssa, Adric and Tegan encourage Leanne to fight Sabaoth and she manages to suppress his return. They manage to vanquish him and the Doctor explains when he projected his mind into Leanne's he implanted a "virus" in it that she passed on to Sabaoth and coupled with having access to his powers as the two were linked, Sabaoth had set itself up for destruction.
The Doctor further explains that he ensured Nyssa and Adric were sent to points that would eventually lead to them becoming spots on her ghost walk and that he lied to Sabaoth about Tegan and put her into a cryo-pod so she could heal and it wouldn't feed on her, then woke her up "almost" immediately after. They then dressed up in cloaks to blend in with the brotherhood that followed Leanne through her tour and that was when they appeared to help her defeat Sabaoth. He then explains that things should be back to normal from now with no more supernatural occurrences, which Leanne is thankful for, saying "she never really believed in ghosts".
- The Doctor - Peter Davison
- Adric - Matthew Waterhouse
- Nyssa - Sarah Sutton
- Tegan - Janet Fielding
- Leanne - Fenella Woolgar
- Matthew - Sacha Dhawan
- Sabaoth - Stephen Greif
- Mrs Stubbs - Carolyn Seymour
- Giles - Philip Childs
- Louie - John Banks
- Nancy - Rebecca Tromans
- The character Sabaoth derives its name from a Latinised spelling of one of the Hebrew names of God found in the Bible, "Tzeva'ot".
- Tegan asks the Doctor if he has ever seen a Peter Cushing film. The Doctor replies "Well actually..." (PROSE: The Day of the Doctor)
- The Doctor explains that the TARDIS is good at traveling, but the more exact point in time they can try to reach, the more unlikely the TARDIS is to find it. Nyssa comments "that's silly" but Adric retorts that it's not at a quantum level. He is, of course, referring to the famous Heisenberg's uncertainty principle, which says that the more certain one is of a particle's momentum, the less certain one is of its position or vice-versa.
- The Doctor claims he's always thought of the TARDIS as a "she", not an "it".
- Adric quotes some sentences written on the TARDIS such as on the front door: "officers and cars respond to urgent calls".
- Traken staircases were very straight and regular.
- The Doctor explains that something is attacking the valency of the bonds in the molecules.
- On Traken, fear is felt but Trakenites try not to show it.
- The Doctor compares an interface between mental and atomic energy to the energy used to boil a kettle translating into a nice cup of tea.
- The Doctor claims he "gabbles" when he's nervous.
- The TARDIS telepathic circuits are mentioned and featured heavily in the story.
- Tegan helps Adric stand using her "drunk passenger" training from her air stewardess training.
- The HADS doesn't always activate because it is selective.
- Tegan mentions Captain Nemo and the Nautilus, both featured in the book 20,000 Leagues Under the Sea.
- Adric mentions Tegan is from Australia.
- The author Dan Brown is mentioned.
- Leanne used beta blockers to calm herself down before her driving exam which she passed on the fifth time, after which the examiner gave her a hug and a wagon wheel (chocolate).
- The Doctor tried to get a cold once, just to see what all the fuss was about.
- Tegan asks if the Doctor is "something like 8000 years old" to which the Doctor replies "more-or-less".
- Artron energy and psychic spores are mentioned.
- Winston Churchill liked bricklaying.
- When Louie tells Leanne that hospitals are using candlelight for light after she blows out the city's power supply, she says it's a very "Florence Nightingale thing to do".
- The movie Poltergeist is mentioned.
- The Doctor is impressed with himself in that he managed to save Nyssa using underwater materialisation.
- Emailing was banned on Traken for being too distracting.
- Tegan says coffee is expensive in the future.
- This story was recorded on 17 and 19 July 2017 at The Moat Studios, London.
- Adric and Nyssa do not appear in the third episode.
- Although the concept of the Heisenberg's uncertainty principle is used here, a proper distinction needs to be made between its depiction in the real world and its depiction in the story. In the real world, the principle typically refers to non-relativistic Quantum Mechanics, in which time is usually treated as merely a type of parameter rather than an observable. It also has a somewhat analogous uncertainty relation, usually dubbed the "Time-energy uncertainty relation". Note that this uncertainty relation is different to the one Heisenberg formulated, although they are related. This is different yet again in Relativistic Quantum Mechanics and Quantum Field Theory. In the context of the story, it is only used as an analogy to explain why the TARDIS over-shoots its destinations a lot. It should not be taken literally.
- The Doctor explains that certain events in time can become fixed points in time if they are observed, however, if they are not observed they can potentially be changed. The Doctor wasn't sure whether he was dead or alive while inside Leanne's head and so claimed that they couldn't see his body to check whether he was dead or alive, lest he really be dead and they create a fixed point in time. He refers to the situation as a "Schrodinger's ghost", a reference to the famous Quantum Mechanics thought experiment Schrodinger's cat.
- Tegan mentioning a Peter Cushing film is actually a meta-reference as Peter Cushing himself played a version of Doctor Who in the films NOTVALID: Dr. Who and the Daleks and NOTVALID: Daleks' Invasion Earth 2150 A.D.
- The Doctor asks rhetorically that if Leanne does "ghost walks" for a living, why would she not want to mention she has an actual ghost in her head? "Ghost Walk" is, of course, the title of the story.
- Sacha Dhawan, who voices the characters Reverend Matthew Doyles and Katya's boyfriend, would later go on to play the Master in 2020 for Series 12 opposite Jodie Whittaker as the thirteenth Doctor. Interestingly, this audio contains more than one actor to have appeared in some capacity on the show (besides the main cast) as Fenella Woolgar voices the central character Leanne and had previously played Agatha Christie in TV: The Unicorn and the Wasp.
- Nyssa tells Matthew about the death of her father Tremas (TV: The Keeper of Traken) and an encounter with a "giant frog". (TV: Four to Doomsday)
- The Doctor refers to the TARDIS as a "she". The TARDIS would later inhabit the body of a female named Idris. He also mentions that it is a living entity. (TV: The Doctor's Wife)
- The Doctor mentions the HADS. (TV: The Krotons, Cold War et al.)
- When preparing for the worst, the Doctor offers some comfort at the sudden change by saying "Deep breath!". This exclamation was used as the title for the first episode of the Twelfth Doctor's era. (TV: Deep Breath)
- Tegan once again exclaims, "Rabbits!" (TV: Logopolis, Frontios, et al.)
- Tegan is still trying to get to Heathrow Airport (TV: Logopolis, et al.)
- Nyssa falls in love again when she and the Doctor visit Stockbridge in the 21st century. (AUDIO: Circular Time: Autumn)
- Nyssa is put on trial for being a witch and the villagers attempt to dunk her by putting her in a ducking stool. A similar trial is performed on the thirteenth Doctor when she is also accused of being a witch. (TV: The Witchfinders)
- After Tegan's energy is drained and she dies, the Doctor puts her body in stasis and says "Brave heart Tegan". (TV: Earthshock et al.)
- The Doctor creates a tomb for himself so that his body will not be found, as the body of a Timelord can be turned into a dangerous weapon in the wrong hands. The Eleventh Doctor's body had to be burned after he was killed on Lake Silencio, as even a single Timelord cell could be dangerous in the wrong hands. The Tenth Doctor burned the Master's body after he refused to regenerate from a bullet wound in order to stop it from falling into the wrong hands. (TV: The Last of the Time Lords, The Impossible Astronaut)