The Keys of Marinus ( TV story ) The Keys of Marinus was the fifth story of the first season of " Doctor Who " and was the second story to be written by Terry Nation . It was notable for its structure , in that it was the first of several " travelling " serial s . Like " The Chase " , " The Daleks ' Master Plan " and " The Infinite Quest " that followed it , " Keys " had the main cast moving to a different setting in almost every episode . It was also the first of 34 six parters in " Doctor Who " . It also introduced the Voord , the first in a long line of deliberate , but generally unsuccessful , attempts to find an enemy as popular as the Dalek s . Episode three , or " The Screaming Jungle " , was the subject of the programme ' s first serious charge of plagiarism . Robert Gould had complained to Donald Wilson that the notion of a story about plant life in the dominant evolutionary position on a planet had been something he ' d outlined to script editor David Whitaker . Whitaker was obliged to write a memo to Wilson on 26 March 1964 , in which he offered a detailed defence against Gould ' s charge . Whitaker ' s successful defence rested on the statement that Terry Nation had independently arrived at the use of hostile vegetation in " Jungle " , and that Gould ' s idea was derivative of , anyway . ( REF : " The First Doctor Handbook " ) Like every other " Doctor Who " story of its era , " The Keys of Marinus " had to find a way to incapacitate the TARDIS to solve the " why not leave ? " problem . However , Nation then created the travel dial s and so had to separate the characters from them as well in order to solve the same problem . Synopsis . The TARDIS arrives on the planet Marinus on an island of glass surrounded by a sea of acid . The travellers are forced by the elderly Arbitan to retrieve four of the five operating keys to a machine called the Conscience of Marinus , of which he is the keeper . These have been hidden in different locations around the planet to prevent them falling into the hands of the evil Yartek and his Voord warriors , who plan to seize the machine and use its originally benevolent mind - influencing power for their own sinister purposes . Plot . The Sea of Death ( 1 ) . The First Doctor and his companions , Barbara Wright , Ian Chesterton and Susan , land on an island and find the beach is made of glass and the sea of acid . The latter is demonstrated when Susan tries to paddle in a rock pool . Barbara accidentally knocks one of Susan ' s shoes , which were placed on one of the rocks around the pool , into the " water " where it dissolves . Susan returns to the TARDIS for a new pair and is followed by a mysterious creature in a rubber suit . While Susan is gone , the Doctor , Ian and Barbara discover four glass submarines , one of which holds an empty rubber suit with a rip in one leg ; it seems that the creature who wore the suit perished in its journey when the acid got inside . When Susan gets to the TARDIS , she finds footprints . She follows them to a tower looming in the distance . As she looks around , the mysterious creature waits around a corner to strike at her . Just before this happens , the wall revolves and eliminates the creature . Finding Susan is not at the TARDIS , the companions go to explore the tower . They decide to split up . The Doctor is brought inside the tower through the spinning walls , as are Ian and Barbara . When Susan is inside , she finds another of the mysterious creatures which , on the point of attacking her , is stabbed by a mysterious , monk - like figure that Susan encountered earlier . Ian discovers one of these creatures fighting with the same man and pulls the creature off him . The creature is thrown back against a wall during the struggle , a hidden panel opens and the creature plunges down a shaft straight into a pool of acid deep beneath the building . The man introduces himself to Ian as Arbitan . He says the creatures are called Voords and explains that he is Keeper of the Conscience of Marinus , a vast computer developed two millennia earlier as a justice machine which kept law and order across the entire planet . For seven centuries it was absolute , radiating its power around the planet and eliminating even evil thoughts . Then a Voord named Yartek worked out how to resist its impulses and corrupted the system . Arbitan explains that the Conscience has now been upgraded to control the Voord again and needs to be activated . Years earlier he saved it from Voord control by separating the five keys that regulate it . The five keys are in different locations — one is in his possession but the others are scattered over Marinus . He suggests that the Doctor and his companions find them , as all his friends and family have failed to return from the effort . The Doctor refuses and leaves for the TARDIS . When he gets there he finds a force field around it . Arbitan says he has been forced to cut the travellers off from the TARDIS so they will find the keys for him . The Doctor and his companions return to the tower to discover that they are to be moved around the island using pre - set travel dial s . As the four teleport away using the dials , Arbitan is overcome and stabbed to death by a Voord that has gained access to the tower . When the travellers reach their destination they discover Barbara , who teleported first , has vanished , leaving only her travel dial , which has blood on it . . . The Velvet Web ( 2 ) . The Doctor , Susan and Ian search for Barbara on the other side of a set of double doors . As they open them an alarm goes off , accompanied by a blinding light . When they stop they see Barbara reclining on a chaise , her every need attended to as if she were a queen . She explains that as she was transported , she panicked and tore at her travel dial , scratching her wrist ; the dial then fell off . One of the inhabitants , Altos , says that they are in the city of Morphoton , an advanced and pacific society . He impresses the travellers with the luxuries , advances and aesthetics of the city . Initially sceptical , the Doctor and Ian are won over by the generous hospitality and beneficence that the people bestow upon them . In the night a young slave - girl , Sabetha , places a small disc on the heads of the sleeping travellers . While Barbara sleeps , her disc falls off . The powerful hypnotic pulse ( the mesmeron ) has no effect on her . Morphoton is governed by four brain creatures with hideous eyes on stalks , which communicate through their life - support machines . The Brains of Morphoton use hypnosis to control the entire city . They have outgrown their bodies , and the entire human population of the city is now subject to their will . When Barbara awakes , she sees the truth : the city is a place of dirt and squalor . She disturbs her fellow travellers with her assessment , claiming that what appears luxurious is squalid . When Susan shows her new dress , she says it is rags . Barbara is taken from her friends but escapes from the clutches of Altos . She finds her way into the dungeons and meets with Sabetha , the same girl who put the discs on the travellers ' heads . Barbara deduce s Sabetha is Arbitan ' s missing daughter ; she is wearing one of the Keys of Marinus about her neck . Meanwhile the Doctor and Ian are taken to what appears to be a state - of - the - art laboratory , but it is just an empty room and the so - called scientific instruments contained within are just old cups and plates . Barbara tries to break Sabetha ' s conditioning but fails . Altos comes to take Sabetha away as the Brains of Morphoton order and stops Barbara ' s escape . Sabetha knocks out Altos . Barbara leaves , promising Sabetha she will return for her . As Barbara prowls the corridors she comes across Ian , whom she embraces . As they talk , she realises that the Brains of Morphoton now control him . They will punish Sabetha , make Susan take her place , put Ian to work , and make the Doctor work in the lab . Ian takes Barbara to the Brains of Morphoton , who order Ian to kill her . He begins to strangle Barbara , but she breaks free and smashes the control room and life support systems . They die , and all the human subjects of the city are freed with their original memories returned . They start to destroy the city . Altos remembers he too was sent to the city by Arbitan , and he and Sabetha decide to join the Doctor and his friends on their quest . The six now split up . The Doctor goes ahead to find the final key in the city of Millennius , while the others venture to find the second key in the next destination . Susan arrives first , wanting to avoid a long goodbye with her grandfather , but soon her ears are deafened by a growing screeching . The Screaming Jungle ( 3 ) . The next location for the five is a dangerous , screaming jungle , which has a particularly debilitating effect on Susan . In the jungle is an ancient temple . Ian finds an archway but it is overgrown with the copious flora . While Ian , Sabetha and Altos look for another entry , the flora reaches out to grab Susan . Even though Ian instructed Barbara not to go into the temple , she finds that the flora can be moved easily . She walks down the passage where she finds a statue — which to her surprise has the key propped on the top . However , when Barbara takes the key , the statue holds onto her and the wall reverses , trapping her . Her companions decide that if she were in real trouble she would use her travel dial to escape , but Ian is sceptical and wants to ensure her safety . He tells the others to go on while he stays to rescue Barbara . As they go , Sabetha realises that the key is a fake . It is shorter than the other one . This gives Ian more reason to stay on . Once they are gone Ian replicates Barbara ' s movements and is likewise trapped . He finds Barbara in a large , booby - trapped hall . Barbara saves his life by shouting as a statue brings its axe down where he was standing . They find doors which need a metal bar to open . Ian finds a bar , but this is also a trap and brings prison walls down around him . Barbara is the victim of a trap when she walks through the doors that have magically opened and is trapped in a net as the dagger - filled roof lowers itself on her . In the temple is an aged and dying scientist , Darrius , who wears a robe similar to Arbitan ' s . He stops the roof to save Barbara . He suspects she may be a Voord . Doubtful she has been sent from Marinus , he takes her time dial to inspect . Ian , who has escaped from his prison , finds them just in time to save Darrius from a creeper . The weak , old man explains the traps of the temple are for the Voord . He too is a friend of Arbitan . Before dying , he tells Ian and Barbara the key is hidden in " D - E - 3 - O - 2 " and points to a door . On entering the next room , they find it is a laboratory . Their attention is drawn to a safe on one of the lab benches , which has letters and numbers on the dial . Ian thinks DE3O2 could be the combination and tries it , but the safe remains locked . He tries a second time , treating the " 3 " and " 2 " as the number of dial turns , but again the safe fails to open . Ian and Barbara come to the conclusion that Darrius may not have been referring to the safe at all , and search the room . As they do so , Ian finds Darrius ' s research , mutating flora with a growth accelerator , increasing the rate of nature . As night falls , the screaming of the jungle starts and tree branches enter the laboratory to destroy the equipment . Ian realises that the letters and numbers are chemical symbols . The two barely retrieve the key from a jar labelled DE3O2 before the vegetation overruns the room . Jumping to the next location , they find it bitterly , paralysingly cold . The Snows of Terror ( 4 ) . Ian and Barbara teleport to an icy wasteland . Unable to move in the crippling cold , they pass out . They wake to a suspicious trapper , Vasor , who saw Susan and Sabetha in a nearby cave but would not risk his life to save them . Ian offers to go and trades his dial for some of Vasor ' s furs , leaving Barbara alone with Vasor . As she clears away dishes , she finds the chain that Sabetha was wearing , along with four travel dials , in a drawer . Vasor sees her looking and becomes angry , saying that he left them to die . This is his plan for Ian , too . He then attacks Barbara . In the wastes , Ian finds Altos , bound and abandoned . Altos tells him Vasor is to blame . They return to the trapper ' s hut and confront him before he can attack Barbara . They order him to reveal the stolen keys in his possession and take them to the caves where he abandoned Sabetha and Susan . Vasor refuses , claiming there are demons in the cave , but the two men force him . The two girls have searched the icy caves themselves and have uncovered a block of ice connected to piping . It is protected by Ice Soldier s , seemingly statues . As they run from the statues , they meet their friends , who have crossed a rickety rope bridge . In revenge , Vasor unties one end of the bridge , trapping them on the other side . While Ian and Altos make a bridge of tree trunks to cross the chasm , they find the next key frozen in the block of ice . They remove the key by turning a dial on one of the pipes , which releases heat from a volcanic spring . This also revives the Ice Soldiers , who chase after the travellers to regain their key . Susan bravely crawls across the wobbly trunks over the chasm and reattaches the bridge . They flee to the trapper ' s cottage to retrieve their stolen dials . Before they use them , Vasor grabs Susan and forces the travellers to fight the soldiers . Vasor is killed by the Ice Soldiers as they break into his cabin . The travellers activate their travel dials . In the next location , Ian discovers the key in a display case , with a dead man lying on the floor nearby . Soon Ian himself is knocked out by a man who steals the key . Before he leaves , the man frames Ian for the murder of the mutilated body by placing the bludgeon in his hand . Sentence of Death ( 5 ) . When the travellers reach the next location , Ian finds himself accused of the murder of Eprin , a friend of Altos who discovered the key shortly before his death . The key has disappeared , and Ian is also accused of theft . In the city of Millennius , the legal system is " guilty until proven innocent " . In other words : Ian is " already " guilty of the crimes of which he is accused , and the sentence will be death unless he is found to be innocent by the court of Millennius . It is up to the defence to prove Ian ' s innocence beyond reasonable doubt . The other travellers are reunited before Ian ' s trial , at which the Doctor will serve as defence counsel . He gets a postponement for two days while he gathers evidence and uses the time to work out what really happened to Eprin . The relief guard , Aydan , is implicated in the murder . To find evidence , Barbara and Susan go to the apartment of Aydan and talk to his wife , Kala , who gives away nothing . When Aydan returns home , he is angry with the women and orders Barbara and Susan to leave . Outside in the corridor , they hear a loud slap and a scream of pain from Kala ; Aydan has obviously hit her across the face . During the trial the Doctor calls Sabetha as a witness . He tricks Aydan into confessing by claiming that one of the already recovered keys is the one that they found in Aydan ' s hiding place . Aydan confesses , but is shot and killed by an unseen person before he can implicate anyone else . As the Doctor sums up , Barbara , Sabetha and Altos are taken out of the trial by Larn . They get a telephone call which Barbara answers . It is Susan , who says that the murderers have kidnapped her and they are going to kill her if the trio don ' t stop investigating . . . The Keys of Marinus ( 6 ) . Altos , Barbara , and Sabetha decide not to tell the Doctor of Susan ' s disappearance and to visit Kala to see if she has any information on who might be connected to her husband ' s death and Susan ' s kidnapping . She says she can ' t help them and breaks down in tears , but begins laughing when the trio leave . Susan is bound and gagged in another room . Kala takes a phone call from someone saying that Ian has been sentenced and Susan can be killed . The trio realise it must be Kala who has taken Susan hostage , as she had talked of the call they got from Susan without any of them having mentioned it . They return before Kala kills Susan , as she did her own husband with a hidden gun , and the plot is uncovered . Reunited with the Doctor , they learn that Kala has admitted her part in the crimes but they must discover her accomplice to prove Ian did not kill Eprin . They are thwarted when Kala swears she was working with Ian . Susan remembers that when Kala was on the phone ; the man said he would pick up the key later that night . The Doctor and the officials of Millenius wait where the Doctor has deduce d the key is being kept — in the mace used as evidence in court . The man trying to sneak it away is Eyesen , the Court Prosecutor . Ian is freed and the trio return to Marinus . Altos and Sabetha have travelled ahead with all but the last key . They do not know that Arbitan has been killed and that Yartek now rules Marinus . Yartek has seized the first four keys and holds Altos and Sabetha prisoner , awaiting the fifth and final one . Yartek attempts to coerce Altos into revealing the location of the last key , but he refuses to give in . Yartek then exploits Sabetha , with whom his is in love , threatening to kill her if he doesn ' t comply . Altos reveals that the last key is with the Doctor , much to Sabetha ' s despair . Yartek then imprisons both of them . The Doctor and his companions arrive and fail to find Altos and Sabetha . They split up , Ian and Susan going to find Arbitan with the key and Barbara and the Doctor going to find Altos and Sabetha . Ian and Susan find someone who appears to be Arbitan , but his face is hidden beneath the hood of his cowled robe ; he warns they must not come near him as he has a dreadful disfiguring disease caused by a power surge from the Conscience . However , this is actually a disguised Yartek . Ian gives " Arbitan " the key and goes to get the Doctor . He finds him releasing Altos and Sabetha , who tell them the Voords now reign on Marinus . Ian says he gave Yartek the false key from the Screaming Jungle . Although pleased , Sabetha and Altos warn the travellers that this will cause the Conscience to explode when the key is put inside it . The travellers run . When Yartek places the false key in the Conscience , the machine duly explodes and he is killed along with the occupying Voords . The Doctor and his friends flee the tower with Altos and Sabetha before the growing blaze overtakes the ancient structure . With the Conscience destroyed , the people of Marinus must now find their own answers , which the Doctor believes is a good thing : man was not meant to be ruled by machines . The travellers say goodbye to Altos and Sabetha who say they will start a new life together in Millennius . Home video and audio releases . DVD release . The DVD was released on 21st September 2009 in the UK , with North American release occurring in January 2010 . As the first three stories are only available at present in the " The Beginning " box set , and " Marco Polo " remains a lost story , " The Keys of Marinus " stands as the earliest " Doctor Who " story currently available on its own . Contents : Rear Credits : Notes : BritBox availability . This story is available for streaming through BritBox ( US ) as part of Season 1 of " Classic Doctor Who " . VHS release . This story was released as " Doctor Who : The Keys of Marinus " .