The Face of Evil ( TV story ) The Face of Evil was the fourth story of season 14 of " Doctor Who " . It introduced Louise Jameson as the Fourth Doctor ' s new companion , Leela . When broadcast , it was originally billed as the start of a new series , due to the six - week gap since the final episode of " The Deadly Assassin " . As originally broadcast , it in fact followed omnibus editions of " Pyramids of Mars " and " The Brain of Morbius " , amongst other , unrelated programmes . ( INFO : " The Face of Evil " ) However , this marketing ploy has not generally been remembered — nor has it been propagated in reference books such as " The Fourth Doctor Handbook " . Synopsis . The Doctor arrives on a planet where two tribes , the savage Sevateem and the technically brilliant Tesh , are at war . He meets Leela , an exile from the Sevateem , and discovers that their god of evil is apparently himself . Plot . Part one . The Doctor , alone in the TARDIS , arrives on a mysterious jungle planet which he cannot resist exploring . He soon encounters Leela , a savage from the local tribe . She denounces him as the Evil One of her people ' s fables . She has been exiled from her tribe , the Sevateem , for profaning their god , the mysterious Xoanon , who speaks to them through the tribe ' s shaman , Neeva . Her father , tribal elder Sole , tried to protect her but died taking the Test of the Horda on her behalf . Now Leela is an outcast beyond the invisible barrier around her tribal home . Neeva , meanwhile , has sent two men to murder her , an action witnessed by Leela ' s friend Tomas . He kills one of them as Leela dispatches the other . In the jungle beyond , she encounters the Doctor , who soon wins her over by defending her from invisible monsters that rampage about , attracted by vibration of any kind . Exploring further , the Doctor finds a sophisticated sonic disruptor . It creates the force field that keeps creatures from attacking the village itself . Leela regales him with more folklore ; the god Xoanon is kept prisoner by the Evil One and his followers , the Tesh , beyond a strange black wall . The Sevateem have decided to launch an attack on the Tesh to free their god . They are led by the combative Andor , who is determined to free his god . He also believes an attack will unite the people . Andor suspects Neeva of being a false prophet , and Tomas tells him of Neeva ' s attempted murder of Leela . Still , Andor believes the attack will succeed and is prepared to go ahead . Two warriors are scouring the jungle when they find the Doctor . They also call him the Evil One and make a hand gesture which the Doctor interprets as the sequence for checking the seals on a Starfall Seven spacesuit . The warriors seize the Doctor but not Leela . They take him to the village council , where his face is shown to the tribe . Andor is convinced the prisoner is the Evil One and has him confined . However , Leela frees him using poisonous Janis thorn s , which paralyse , then kill the victim . The Doctor is horrified by this . He instructs her , " No more Janis thorns , ever . " The pair flees the village and heads to a clearing beyond , where the Doctor is greeted by a stunning sight . Carved into a mountain nearby is a relief of his own face . Part two . The Doctor cannot recall clearly why his face is here . He persuades Leela to return to the village to learn more , despite their death sentences . They return to Neeva ' s holy tent . The Doctor inspects the ancient tribal relics , recognising them as artefacts from an Earth survey expedition . He also finds a transceiver used by Neeva to hear the commands of Xoanon . It speaks with the Doctor ' s own voice , exhilarated at hearing the Doctor , saying , " At last we are here . At last I shall be free of us . " They head off to inspect the dark wall that stands at the entrance to the realm of the Evil One . The Doctor deduce s it is a primitive time barrier . He is certain the Sevateem warriors will be massacred if they attack the fortress of their enemy , the Tesh . From afar they see the massacre unfold , as laser beams cut down warriors armed only with crossbow s and other basic weapons . Half the tribe is lost in the assault . One of the elders , the devious Calib , is first back at the camp , where he finds the Doctor and Leela . He is evidently intent on using the Doctor to break Neeva ' s hold on the tribe by exposing the faith in Xoanon as mythology . Leela ' s friend Tomas also arrives . He is apalled to find Calib has stabbed Leela with a Janis thorn to prevent her exposing his schemes . The Doctor gets Tomas to help him move Leela to Neeva ' s tent , where he uses a bio - analyser to synthesise an antidote to the poison . When the surviving warriors return , the Doctor , Leela and Tomas are invited to address the tribal elders in defence of their lives . Leela makes matters worse when she accuses Xoanon of causing the trap at the wall . Calib intervenes to suggest the Doctor is not the Evil One . He suggests this be proven by getting him to take the fabled Test of the Horda . In the centre of the village is a pit full of Horda , two - foot - long worms which hunt in packs and react to the movements of their prey . They are reputed to strip flesh from a man in an instant . The Sevateem evolved the Test of the Horda as a trial of justice and bravery . It involves the defendant standing on a board over the pit , who then must shoot a rope attached to a boulder that is pulling the board out from under him . The Doctor is given a crossbow . He must fire it at a precise moment to sever the rope without making him fall into the pit — the fate of the guilty . The Doctor succeeds , is proven a non - malign influence and freed . He proceeds to examine some relics of the tribe and repair a disruptor gun . He also tells some of the tribe that the Sevateem are the descendants of a " survey team " from a Starfall Seven Earth colony ship . The Doctor and Leela go to examine the face in the mountain ; they climb into it by scaling the Doctor ' s teeth . Neeva returns to his tent , where the voice of Xoanon tells him the tribe will be destroyed . The mysterious being shuts down the sonic disruptor , leaving the village open to attack from the invisible beings . These descend on the village , killing indiscriminately and crushing Andor to death . Tomas uses the disruptor gun built by the Doctor to expose the true appearance of the invisible beings : ferocious , angry versions of the Doctor ' s face . Part three . Leela and the Doctor notice a figure in a space suit in the " mouth " entrance and follow it through a projection of a wall . Beyond this barrier is a rocket , which the Doctor recalls as belonging to the Mordee Expedition ; his memory of events earlier in his incarnation are returning . Xoanon has detected the Doctor . When he reaches the ship , the god - creature is ecstatic that " we are here " and also maniacally pledging that " we must destroy us " . The Doctor and Leela meet three of the Tesh who serve and worship Xoanon . They are human too , but technologically advanced and possessing telepathic abilities . The Doctor deduce s both Sevateem and Tesh are descendants of the same crew from the Mordee Expedition , with the Tesh ( or technicians ) involved in the same deadly eugenics exercise as the Sevateem . The invisible creatures which attacked the Sevateem are also part of the same deranged scheme . Xoanon is a highly sophisticated computer , designed to think independently . The Doctor repaired Xoanon but forgot to wipe his personality print from the data core , leaving the computer with a split personality . The Doctor and Leela are soon imprisoned , then escape and find the device used to communicate with Neeva . The Doctor , speaking as Xoanon , instructs Neeva to tell Calib , who is now tribal leader , to lead the Sevateem survivors through the mouth of the carved face in the mountain . Calib accepts this instruction and leads them into the safety of the mouth , where the invisible beings cannot threaten the tribe . With Leela keeping guard and holding the Tesh at bay with a disruptor gun , the Doctor ventures into the computer room of the ship to confront Xoanon . He blames himself for creating the computer ' s maddened split personality . He now attempts to persuade it to shut down . Xoanon refuses and channels a vicious mental attack at the Doctor . As the Doctor writhes on the floor , Xoanon booms : " Who am I ? " Part four . Leela rescues the Doctor from the mental assault . As he recovers , he warns her of Xoanon ' s power . Moments later they realise the computer has electrified the walls to kill them . The Tesh become more purposeful in tracking them down in the spaceship . The Tesh also come under attack by Calib , Tomas and the survivors of the Sevateem , who reach the spaceship too . This diverts the Tesh while the Doctor and Leela return to the computer room . Xoanon briefly takes control of Leela ' s mind , as he does of most of the Sevateem . The Tesh and Sevateem soon converge on the computer room too and interrupt the Doctor as he tries to repair Xoanon . The computer has triggered the countdown to an atom ic explosion . Elsewhere in the ship Neeva is alone and crazed , his faith in Xoanon shattered . The shaman uses the disruptor gun against one of the images of Xoanon / the Doctor projected through a wall . The ensuing blast kills Neeva but also interrupts Xoanon ' s control of its subjects , allowing the Doctor to resume and complete his repairs . Xoanon ' s circuits explode , knocking the Doctor out . Two days later the Doctor wakes up to find himself aboard the spaceship in Leela ' s care . She explains Xoanon has been quiet , and he interprets this as success for his extraction experiment . They visit the computer room and find Xoanon ' s identity and sanity restored . The computer confirms it was running a eugenics experiment and thanks the Doctor for his repair work . The Doctor contacts the survivors of the Tesh and Sevateem to tell them Xoanon is cured and able to support their new society . Unwilling to help them sort out the political question of which group should control the planet , the Doctor heads off to the TARDIS , followed by Leela . She insists on joining him on his travels . When the Doctor refuses , Leela runs past him and into the TARDIS . The Doctor follows Leela inside , telling her to come out . He is heard to say " Don ' t touch that . . . ! " , but it ' s too late . Leela has started the dematerialisation process , and the TARDIS departs from the planet . Home video and audio releases . Video releases . This story was released on VHS in May 1999 in the UK and in March 2000 in the US . DVD release . The DVD was released in Region 2 on 5 March 2012 and in Region 1 on 13 March 2012 . Special features include :