Cobwebs ( audio story ) Cobwebs was the one hundred and thirty - sixth monthly " Doctor Who " audio story produced by Big Finish Productions . Released in 2010 , it began the first season of Fifth Doctor stories for that year . It was the first new story to feature stars Peter Davison , Sarah Sutton , Janet Fielding and Mark Strickson since the television story " Terminus " in 1983 , thus beginning a " series " of 15 audio dramas for that TARDIS team across five years , finally reaching a conclusion with the audio story " The Entropy Plague " in 2015 . Publisher ' s summary . " You know what cobwebs mean . Spiders . . . " In search of a cure for a sickness that ' s so far claimed six billion lives , scientist Nyssa arrives at an abandoned gene - tech facility on the toxic planet Helheim . " Hellhole " , more like . Nyssa ' s not alone . The TARDIS has also been drawn to the Helheim base — and in its cobweb - coated corridors , she soon runs into the Doctor , Tegan and Turlough , her travelling companions of half a century past . But who , or what , has engineered this strange reunion ? The Black Guardian , perhaps ? The answer ' s here , in the dark . With the Cractid s . In the cobwebs . Plot . Part one . Tegan and the Doctor are embroiled in an argument about Turlough . Tegan insists that he shouldn ' t be trusted whilst the Doctor says that he chose the right side when he was called upon . When Turlough enters Tegan storms off . Meanwhile the Doctor ' s previous companion Nyssa is hovering above the planet Helheim with her paranoid android Loki . They are there to source out the abandoned research centre on that planet . They pick up a radio distress signal from 40 years previously warning that the planet has gone into quarantine . Despite his protestations Nyssa sends Loki to investigate . Back in the TARDIS , Turlough apologises to Tegan and tells her that he wants to be returned to his home . Tegan seemingly relents but as they begin to land the TARDIS goes into free fall . As they go to the control room they find the Doctor attempting a forced landing . While the Doctor does this Tegan wonders if this is a Black Guardian trap but the Doctor refutes this . Loki finds no signs of life or any harmful pathogens . Nyssa joins him in the base . Loki informs Nyssa that there are traces of a series of subterranean ruins underneath the base — Nyssa says they will investigate . Nyssa seems concerned about the amount of cobwebs in the base but her fears are allayed when they discover robot maintenance spiders . Nyssa finds the power generators and manages to switch the lights on . When she does Nyssa sees a number of large crab like creatures approaching her . She begins to panic and implores Loki to neutralise them , however Loki cannot see or sense them . Nyssa screams in panic as the animals crawl on to her . The Doctor , Tegan and Turlough emerge in the middle of a base . The first thing the Doctor notices is the preponderance of cobwebs but with no sign of dust that are dating them . His concern is allayed when he sees one of the robot spiders on Tegan . The trio begin to investigate the base . They note that the quarters see no sign of any personal effects and imply a quick escape . They hear a noise that draws them into the next room . Loki approaches them threatening them to remain still . Even though they do he fires a stunning beam at the Doctor . Nyssa emerges from the darkness and calls Loki off . The Doctor and Tegan seem surprised to see their old friend there . They discover that the events of their parting , a mere two days ago for the Doctor and Tegan , were fifty years previous on Nyssa ' s timeline . She explains that she is here to try and find a cure for the deadly Richter ' s Syndrome that is sweeping through the universe and has killed six billion people . The people at this base were supposed to be sourcing the cure but communications dropped . The group split up . The Doctor and Turlough go to explore the ancient ruins whilst Nyssa and Tegan with Loki go to access the computer database . As soon as they access the main deck of the base Loki warns that he feels a presence all around them . The voice of the computer greets the humans stating that he knew they ' d return . Down in the ruins the Doctor hypothesises that this civilisation must have had great technological power if it was their infrastructures that dragged the TARDIS off course . As they Turlough asks about how long the Doctor knew he was working for the Black Guardian and if he trusts him , which the Doctor replies that he trusts Turlough as Turlough trusts him . Turlough then sees a figure approaching them — the Doctor cannot see anything . Turlough screams with panic as he is " fired at " . The computer system refers to himself as EDGAR and says that the travellers have been here before . Nyssa wonders if this may have happened later in their time line but earlier in the timeline on Helheim . The computer begs the humans to " pity him " . The Doctor rushes over to Turlough who seemingly just collapsed . Turlough informs him of what happened . When the Doctor tries to put it down to hallucinations , Turlough says that he actually felt the rays of the gun enter his body . The Doctor points out there is not a mark on him . The Doctor and Turlough go and join their friends on deck . When Turlough recounts his story Nyssa states that she had a similar experience . The Doctor states this to be a telepathic memory projection coming from the previous crew . Tegan points out these must be the last memory ' s of the crew . When the computer speaks to the Doctor he decodes that EDGAR must stand for Ersphile Data Gatherer and Research . The Doctor asks EDGAR to show him the crew . EDGAR projects the three original member of the crew . Tegan asks of there have been any other humans on the base . EDGAR shows footage of the travellers — the Doctor immediately stops this saying that they cannot know of their own future . Tegan worried and panicked asks EDGAR where the crew are currently . EDGAR answers that they are in the medical bay . Despite the protestations of the Doctor , Tegan marches to the medical bay where she orders Loki to open the doors which have been locked from the inside . When they enter they see four decomposed bodies cocooned on the beds . The bodies are wearing exactly the same clothes of the Doctor and his companions are at this moment and the travellers surmise that these are their remains . Part two . Tegan refuses to believe that they are the bodies found in the medical bay . The travellers argue about if the remains are them so they ask Loki to scan them , when he does he finds the remains are the travellers but Tegan still refuses to believe him so the Doctor and Nyssa take samples to perform tests . While the results are coming in Turlough hypothesises that the base was not only working on the virus as he feels that the thickness of the doors are over zealous for such activity . The tests results show that the skeletons are genetically identical to the travellers and were also the same age as they currently are . The Doctor also refutes the ideas that the remains are clones or from an alternative timeline by asking Nyssa to cut a Turlough ' s jacket before pointing out a corresponding cut on the jacket found on the corpse . Tegan starts to believe that the remains are them and storms off scared . The Doctor follows after her and she tells him that they should leave and go somewhere else so that the future won ' t happen . The Doctor tries to explain why this can ' t happen because it would cause a paradox , but Tegan is too scared to listen to him and says she won ' t let the future happen . EDGAR overhears this conversation and states he won ' t let them leave him alone again . Meanwhile , Nyssa investigates the data logs which is populated by memory upload from the original crew . Turlough mentions they shouldn ' t be looking into what happened but Nyssa says her mission to find the cure is too important . They find a recording of Cardell saying they found a cure for Richter ' s but the message is incomplete and all details of how the cure was found are deleted . Nyssa wants Loki to link with EDGAR but discovers he has gone . The Doctor is still trying to talk to Tegan about their future , when a door that only Tegan can see appears . The door starts to open and Tegan starts to have difficulty breathing , the Doctor realises this is another memory projection of one of the crews final moments and gets EDGAR to stop it . The Doctor wonders why EDGAR has been programmed to show these specific memories . Nyssa and Turlough go back to Nyssa ' s ship and find Loki . He says that EDGAR is going to kill them but can ' t explain why or how he knows this . He begs for them to leave . They spot the robot spiders in Nyssa ' s ship having come in through the fuel ducts . They are sabotaging the ship . The hyper ship drives start to fire and they evacuate as the ship will now blow up as its on the ground . EDGAR is pleased as they can no longer leave . Tegan is recovering from the hallucination when they hear the explosion . The travellers reunite and theorise that EDGAR is behind this to ensure they can ' t leave . EDGAR says he is trying to save them from their fate so he isn ' t left alone . He knows they can time travel and wants them to go back and stop the crew being killed . Tegan wonders where the crews bodies are , and if the remains are their future then where is their TARDIS . Turlough thinks the alien ruins are involved , so the Doctor says they must now go back in time to find out what happened . Tegan and Turlough are against this as they want to prevent their deaths , but the Doctor and Nyssa say they must . EDGAR then commences a self destruct option that will destroy the whole research centre , but Loki has vanished . The Doctor sends Tegan and Turlough to the TARDIS while he and Nyssa go to look for Loki . Loki is found in the control room and the Doctor tries to stop the self destruct but EDGAR commits suicide so that he can finally die . Despite EDGAR ' s " death " the countdown cannot be stopped . With nothing else to do they head back to the TARDIS . Back at the TARDIS they are about to take off but Loki is still outside , luckily he arrives in the last second and they escape the explosion . 40 years , 2 months and 2 days in the past Cardell is saving a memory record when the TARDIS appears . She calls Valis and Bragg and gets them to go to where it has landed . Inside the TARDIS they remark on how new the base looks and notice the crew don ' t appear to be pleased to see them . Back outside the crew are wondering what the TARDIS is , wondering if it is enemy agents from independent companies . In the TARDIS , Tegan wants to warn the crew , but the Doctor says they can ' t as its against the rules of time travel . Nyssa tries to stand up for the Doctor , but Tegan is too cross and thinks the Doctor is wrong . The Doctor says none of them have to come with him outside and Tegan and Turlough choose not to , but Nyssa says her mission comes first and her and Loki will go with him . As they go outside they are held at gunpoint but they convince the crew that they were sent by the company to inspect the progress they have made on Richter ' s syndrome . They explain the TARDIS away as being an escape pod from their damaged vessel and explain that their papers were on the damaged ship . They use their knowledge of the crew to persuade them they have files on them . Valis says they have not made much progress on a cure , much to Nyssa ' s horror . Cardell and Valis say they will show them their research warning that Bragg will kill them if they turn out to be spies . Inside the TARDIS , Tegan and Turlough watch all of this and Tegan remarks that they are safe unlike the Doctor and Nyssa . Turlough wonders if staying in the TARDIS is the action that will lead them to end up dead in the future , and suggests they should try and warn the crew as it might change their own futures as well . Tegan and they both leave the TARDIS . In the laboratory , Nyssa recognises the crab like creatures from the memory projection in cages and Cardell tells her they are called Cractid s . They are the only creatures with an immunity to Richter ' s syndrome and they have been trying to replicate their immunity in humans by infecting them . Nyssa suggests making the Cractid immunity part of the human immune system instead of the other way around — an idea that is met with positivity by Cardell . Bragg checks up on the Doctor and Nyssa by phoning the company . He finds out that they have been lying and so plans to kill them , he then locates Tegan and Turlough leaving the TARDIS . He is interrupted by Loki and destroys him when Loki tries to stop him from killing the travellers . Back in the laboratory , Nyssa asks Valis what she used to do , but she tells her that the entire crew had their memories wiped before starting the mission and they get them back after the end of the mission . Cardell is suspicious about why the Doctor does not know this considering he ' s from the company but he pretends to have forgotten . Tegan and Turlough are trying to find a member of the crew when Bragg finds them and holds them at gunpoint . They try to warn him about the crew ' s forthcoming deaths but he believes they are threatening him . They are led away . Valis is injecting the modified cure into a Cractid , when Bragg brings Tegan and Turlough in , he tells Cardell about the travellers lies , and the travellers are taken to the medical bay . There they are strapped to the beds and are to be given lethal injections . The Doctor points out this is how they end up dead in the future and postulate that it seems their futures have caught up with them . Part three . Just as the injection is about to be delivered Vallis stops the procedure . She shares the news that the cure for Richter ' s has been found and that they should utilise the four trespassers as test subjects . She asks for Nyssa first . The rest of the travellers are left with Banks . He refuses to believe they are from the future . He states that If they were from the future they would know the secret of the ruins . The Doctor tempts Banks into showing them this secret . In order to ensure they do not harm Banks he keeps Turlough behind as a makeweight . Cardell is us mounded to the main room by EDGAR and is told that now the objective of the mission has been met the crew are now allowed their memories back . Cardell ' s memories are restored including the real purpose of the mission : the development of a more deadly strain of Richter ' s which the corporation can sell a cure for as well as the fact that the lives of her children are in danger if she does not comply . Down at the ruins Banks shows Tegan and the Doctor an inscription that on , y he can see . He explains that it bears the names of the crew and states that that shows that they are bound to be here . As they come up from the ruins Cardell collects the Doctor and Tegan to take them to the lab . When Vallis gets Nyssa into the lab she asks her how she knew how to cure the disease . Vallis explains that it is because she is from the future and knows how they began the process of the cure . She also refuses to have her memories back saying their must have been a reason why she chose to come on the mission . Banks is summoned to the control room and is given his memories back . He remembers that he is an agent from independent company who has been tasked with gaining the antidote . Banks reprogrammed EDGAR so that it will only obey him . Cardell delivers the Doctor , Turlough and Tegan to the lab and is confused to see that Nyssa hasn ' t been experimented on . Vallis explains she has no intention on performing experiments on live human samples . Cardell says that she has no such qualms and will begin on Vallis . They are interrupted by Banks who comes in wielding his weapon . Turlough , remembering the memory from the future , tells the Doctor and Tegan to get down , remembering that this is how one of the crew dies . Banks fires . The Doctor and Nyssa run out of the room leaving Turlough and Nyssa behind . As they run they hear EDGAR short circuiting over the tannoy . They decide to go and seek out the cause . Back in the lab Turlough is surprised to discover that Vallis is not dead . Banks grabs Cardell and places her in the Cracktid cage before releasing the creatures . The Doctor watches this from the control room but cannot override the system . As the Doctor tries to solve the situation Tegan asks how the memories that they experienced in the future could be the final memories of the crew as they wouldn ' t have been uploaded . The Doctor agrees only to see Banks stun the Cracktids and upload the memories to EDGAR and give the demand that all future memories should be wiped , making these the last memories the crew had . Banks takes Vallis hostage and leaves Turlough , Nyssa and Cardell locked in the lab in imminent danger as soon as the Cracktids gain consciousness . In the control room EDGAR explains that because the crew died at this date he has to kill them as it is now looking like this is not going to happen . Tegan and the Doctor wonder how EDGAR gained this knowledge of the future . The Doctor notices that the voice of EDGAR is also coming from the damaged husk of Loki and explains that the future EDGAR must have come back into the past and merged with the historical EDGAR to create this paradox . The Doctor manages to short circuit the door meaning that his friends can escape , however he cannot close meaning that the Cracktids are now free to roam the ship . He goes in search of Banks . Banks cancels all data on the antidote to the virus in order to retain the value of his knowledge . He destroys Vallis memories before joining the crew before leaving her behind a locked door with the Cracktids approaching from behind . Banks plans to leave through an emergency pod . Before he leaves he fakes his own death by ordering EDGAR to depressurise the airlock to 0 before repressurising it and asking for his records to be wiped just before the repressurising . He is annoyed to find that the fuel in the ship is at zero and he has to draw fuel from another part of the ship , delaying his escape . The Doctor , reunited with all his companions , are chased by Cracktids into the medical bay . The door is permanently locked from the inside . The Doctor explains that this must be how their bodies are discover long in the future and that they have consigned themselves to their own deaths . Part four . The Doctor contacts Cardell to ensure that she is safe . She radioes back saying that she ' s fine but Banks is about to escape . Nyssa comes up with the plan to use the fact EDGAR placed a part of itself in Loki to see if it can counteract Banks demands . Nyssa sends the robot maintenance spiders to stop the power from the solar banks to power the escape pod . This plan works . When Banks tries to counteract it EDGAR insists he is Loki . Back in the medical bay the Doctor insists that this can ' t be their fate as their was no second TARDIS . Turlough comes up with the idea that they can use a sonic bast like Banks used to eliminate the Cracktids waiting outside . They do this . Turlough wants to kill them but the Doctor forbids him saying that to kill is only their instinct . The Doctor goes to seek out Banks . In the control panel Cardell tries to record the research but is stopped by Banks . Banks overrides EDGAR and deletes all traces of Loki and orders EDGAR to send spiders to fix the solar banks . The Doctor enters , distracted by this Cardell manages to knock Banks out . Cardell , Nyssa and Tegan go to get the research files whilst Turlough and The Doctor wait for Banks to wake up . Once they get the files Cardell orders that she is given the new super virus . The two women refuse and a scuffle ensues . Tegan manages to escape with the cure however in the scuffle the vial containing the stronger strain of the virus is broken and released into the air . Nyssa warns the Doctor . Banks wakes to hear this and laughs saying that they will die altogether after all . EDGAR watches over this pleased that his plan is coming together . The three men decide to go and meet Tegan at the medical bay to receive the cure . As they leave the control room EDGAR locks the door after them . As they leave the research centre to meet Tegan at the medical bay , Cardell cramps up the first sign of Richter ' s Syndrome . Cardell orders Tegan to leave her and come back later with the cure . In the Medical Bay the Doctor hands out the cure to his companions . Banks refuses the cure saying that his company wanted a sample of the disease and the cure and he plans to give it to them . He takes Tegan hostage and orders the Doctor to hand over the cure . He himself will be the sample of the disease . As he leaves , Banks triggers the decontamination of the centre . The Doctor follows . As Tegan is dragged through the corridors she sees the Cracktids waking up . Banks bumps into Cardell . Banks tries to reason with Cardell , stating that there is room on the escape pod for the pair of them . Cardell says she only knows one thing she can do now and threatens to blast a hole in the wall of the base . Sucking the disease and them all in to space . The Doctor sneaks in and gets Tegan ' s attention . He finds some space suits and the pair put them on . Cardell blasts a hole on the wall which sucks her , the disease and the Cracktids out . Tegan and The Doctor look to see where Banks went . Banks managed to escape to the pod and begins the process of blast off . The Doctor and Tegan holding on to the side of the ship , see the pod start to take off and pull themselves into the air lock . As they brush themselves down they see the spiders immediately begin the process of rebuilding the ship . Nyssa , left in the medical bay , tries to reason with EDGAR . She points out that EDGAR knows they come back in the future so how can the research centre be destroyed now . EDGAR admits that this would create a paradox so postpones the decontamination . Banks has no fuel left to go into warp so cryogenically freezes himself . The Doctor and Tegan return to the TARDIS and pilot it to the medical bay . Before they leave they ask how their bodies can be there . The Doctor says he will show them . Before they leave the doctor promises EDGAR they ' ll be back . EDGAR is left pining after his new " crew " . Inside the TARDIS the Doctor tells his companions to look at the screen and shows them the medical bay at a rate of one second per day . They watch as the spiders enter and try and rebuild the Doctor and his companions . The Doctor explains that the bodies weren ' t decomposed they were being built up by EDGAR as a replacement crew before EDGAR went into hibernation prior to their original visit . Nyssa orders to be taken back home . The Doctor seems put out that she won ' t travel with him more . She states it is her mission to cure Richter ' s Syndrome and she has the information she needs now . The Doctor agrees but Tegan points out that , knowing the TARDIS it might be a while before they find themselves back in Nyssa ' s time . Nyssa agrees with this and goes to look for her old bedroom . Thirty years in the future banks is unfrozen . He finds himself on a crowded passenger ship . He orders the ship to be quarantined but his finder informs him it is too late . The passengers have all already left — taking Richter ' s Syndrome with them .