Warriors of the Deep ( TV story ) Warriors of the Deep was the first story in Season 21 of " Doctor Who " . It marked the return of two enemy races last seen during Jon Pertwee ' s tenure as the Third Doctor : the Silurian s and the Sea Devil s , who make their only televised appearance in the same story . The Silurians and Sea Devils hadn ' t appeared in the series since " Doctor Who and the Silurians " and " The Sea Devils " ( respectively ) , and this story marks the final televised appearance of the latter species . Off set , this story was notorious for its troubled production and poor execution , with particular regard to the Myrka ( which was negatively compared to a pantomime horse by critics ) . This story was beset with numerous production problems and even political considerations ( Margaret Thatcher had called an election when production began , and the reference to two superpowers in the story would be seen as a reference to the Cold War ) . There were a number of continuity problems concerning the Silurians and Sea Devils in the original script . ( DOC : " The Depths " ) Editing removed many , but some remained in production . Synopsis . The Fifth Doctor , Tegan and Turlough arrive on Sea Base 4 , a nuclear warhead station under the sea that has some very nasty neighbours . Plot . Part one . The year is 2084 , and there is a cold war in progress . The world is divided into two opposing superpower blocs . One of the blocs has created a secret underwater base , Sea Base 4 , which is strategically positioned and has nuclear weapon s aimed at the opposing bloc . As a security measure , the base ' s proton missile s can not be activated unless a trained human operator can " sync " his / her mind with the computer and authorise their deployment . However , the bridge sync operator , Lt . Michaels , has been mysteriously killed and has been succeeded by his inexperienced apprentice , Ensign Maddox . Maddox is nervous , fearing he is not ready to take over as sync officer and will not be able to cope if a missile run is ordered . An unidentified reading is detected by the base ' s long - range sensors , but the base ' s commander , Vorshak , and one of his officers , Bulic , dismiss it as nothing more than a glitch . The reading on the sea base ' s sensors is , in fact , an undersea craft ; on board is the Silurian Icthar , with his subordinates , Scibus and Tarpok . Inside the TARDIS , the Fifth Doctor has set coordinates for Earth , telling Turlough he has promised Tegan to show her some of her planet ' s future . The TARDIS materialises in orbit over Earth , but is confronted by a robotic security satellite , Sentinel Six , which demands the TARDIS transmit the proper security code . Meanwhile , the sea base sends out an unmanned probe to check on the identified reading , just to be sure . Taking note of the probe , Scibus is concerned that they will be detected , but Icthar sends a Myrka , a large aquatic reptile with the ability to electrocute other organisms that the Silurians control , against it ; he assures Scibus that the creature will destroy the probe before they are detected . They then descend to a secret underwater berth where their cousin - species , the Sea Devil s , have long been in hibernation . Sea Base 4 undergoes a missile run and Maddox is synched to the computer ; it turns out to only be a practice drill but when it ends , Maddox is overwhelmed with anxiety and faints . The base ' s chief medical officer , Doctor Solow , declares Maddox is unfit for duty . Vorshak is concerned ; until Maddox can return to his duties or a replacement is assigned , the function of the base is compromised . Another officer , Nilson , suggests to Vorshak that they use a special security disk to reprogram Maddox ' s brain and help the sync operator cope with his job . Vorshak agrees and releases a duplicate program disk to Nilson and Solow , who take Maddox to the medical area ' s psycho - surgery unit . Nilson and Solow , however , are actually enemy agents for the opposing bloc ; they plan to program Maddox so that he will destroy the nuclear weapons computer . Exiting the TARDIS , the Doctor , Tegan , and Turlough find themselves in a chemical storage area . From the design , the Doctor accurately surmises the year and is aware of the time period ' s cold war . Turlough signals for a lift , inadvertently triggering an alert in the base ' s security system . A team led by Bulic is dispatched to investigate . The Doctor sets a reactor to overload in an attempt to avoid capture ; this allows Tegan and Turlough to escape , but the security guard catches up to the Doctor . The two struggle and the Doctor falls over a ledge into a pool of water . Part two . The Doctor swims underwater and escapes through a hatchway . Tegan and Turlough escape through a bulkhead , sabotaging it so they cannot be followed by Bulic and his security guards . A security guard is electrocuted while trying to open the bulkhead . The Doctor finds the guard and takes his radiation suit . Meanwhile , Turlough allows himself to be captured in order to give Tegan a chance to escape . In the underwater berth , Icthar revives the Sea Devil warriors of Elite Group One from their hibernation and orders their commander , Sauvix , to attack Sea Base 4 . They may kill the humans , but Icthar needs the base intact and undamaged . Turlough is captured when a bulkhead seals between him and Tegan . Turlough is taken to the bridge for questioning . The Doctor meets up with Tegan . They head towards the bridge . Outside of the bridge , the Doctor leaves Tegan in hiding while he enters the bridge to find Turlough . The Doctor enters the bridge and starts to negotiate the release of Turlough . Tegan is found by Preston , a worker on the Sea Base , who takes her to the bridge . A Silurian battlecruiser comes into view of the base and Vorshak orders an attack on it . The Doctor tells Vorshak to call off the attack , stating that the Silurians are a noble race . Vorshak ignores him and the Silurians use a particle suppressor to neutralise the base ' s defences . In the confusion , Solow and Nilson use Maddox to sabotage the station . One of the base ' s personnel , Karina , discovers this and attempts to stop Maddox , but Solow and Nilson force him to kill her . The Silurians then launch their attack , dispatching the Myrka against the sea base ' s airlock 1 and the Sea Devils to assault airlock 5 . The Doctor and his companions head to airlock 1 while Vorshak , Preston , and a team head to airlock 5 . The Myrka breaks the door down , trapping Tegan and killing some of the base ' s crew with its electric touch ; the Doctor stays to free Tegan , but the other other crew members retreat , sealing the bulkhead and therefore leaving the Doctor and Tegan trapped in the airlock with the Myrka . Part three . The Doctor is able to free Tegan when the Myrka steps on on side of the door raising up the side Tegan was trapped under . They are then trapped by the bulkhead and the Doctor is unable to open the door . The Doctor removes the rifle ' s power pack and tosses it at the Myrka causing the power pack to explode and temporarily blind the Myrka . Turlough races to the bridge and threatens Nilson with a rifle to open the airlock in which the Doctor and Tegan are trapped . After Nilson complies , the Doctor and Tegan escape and head to Airlock 5 . This also releases the Myrka . The creature begins making its way toward the bridge , killing more of the base ' s personnel . The Silurians prime up a device called a manipulator and prepare to enter the base . At Airlock 5 , the Doctor tells Vorshak that he has an idea to defeat the Myrka and that he needs one person to help . Vorshak tells Preston to help him . Preston leaves Vorshak at airlock 5 and heads off to help the Doctor and Tegan stop the Myrka . The Sea Devils blow open airlock 5 and ruthlessly kill a defender , suffering no casualties of their own . Vorshak manages to survive and orders a retreat . The Doctor works with Preston to modify an ultraviolet converter to fight the Myrka with . Vorshak orders Nilson to radio their superiors to inform them of the attack . Nilson and Dr Solow discuss what they should do and Nilson tells Dr Solow to flee in an escape pod while he continues manipulating Maddox ' s sabotage . Dr Solow tries to flee the base with the reprogramming disk , but is killed by the Myrka . The Myrka comes around a hallway corner towards the Doctor and is destroyed by the ultraviolet converter . The Sea Devils continue their push towards the bridge , killing any crew that stand in their way . The Silurians follow in their path . Vorshak reaches the bridge with Preston and finds Nilson alone and not setting up the communications with their superiors . Suspicious , he has Preston look for Maddox . She finds him sabotaging the computers . Vorshak tries to stop Maddox , but Maddox throws him to the ground . Maddox collapses because of the effort from the manipulation by Nilson . Preston and Vorshak confront Nilson and attempt to take him into custody but he pulls a gun on them . The Doctor and Tegan enter the room and are captured as well . Maddox tries to stop Nilson , but Nilson overloads the control unit for Maddox ' s brain , killing him . Preston tries to grab the gun that Maddox dropped and the Doctor tries to knock the gun out of Nilson ' s hand , but Nilson knocks over the Doctor and takes Tegan hostage . Nilson takes Tegan and leaves the bridge to try and escape in an escape pod . Bulic and Turlough are still retreating while fighting with Sea Devils but as they step through a doorway , they walk right into another group of Sea Devils and are captured . They lock Turlough and Bulic in the crews ' quarters . The Doctor runs after Nilson and makes it back to the ultraviolet converter . Nilson comes around a corner with Tegan still hostage and confronts the Doctor . The Doctor blinds him with the ultraviolet converter . The Doctor and Tegan head back towards the bridge and Nilson , still blind , stumbles around the corner into a group of Sea Devils . They kill Nilson . The Sea Devils come around the corner and capture the Doctor and Tegan . Part four . The Sea Devils take the Doctor to the bridge , now under the control of the Silurians . The Doctor recognises Icthar from his third incarnation and confronts him about the massacre in the base . Icthar explains to the Doctor and Vorshak his plan to destroy mankind by starting a war with the base ' s missiles . The nations of the world will retaliate , wiping one another out . They undo the damage caused by Maddox ' s sabotage and connect the manipulator to the systems . Turlough , meanwhile , has been trying to loosen a grille that leads to a ventilation shaft when he hears someone approaching . The door opens and the Sea Devils push Preston and Tegan into the room . Once they leave , Turlough loosens the grille and Tegan and Bulic escape as Turlough considers trying to escape to the TARDIS . Tegan and Bulic find their way to a door to the bridge and Bulic gestures to the Doctor who then escapes unnoticed from the bridge . They make their way to the storage room and try to find something to use against the reptiles . They discover some cylinders of Hexachromite gas , which is lethal to all reptile life . A Sea Devil discovers the Doctor ' s presence and attempts to shoot him . He misses the Doctor and hits one of the gas containers which sprays all over the warrior . As a result , the warrior begins to dissolve . Preston urges the Doctor to use the gas on the Silurians and Sea Devils . The Doctor adamantly refuses , accusing Preston of advocating genocide . Turlough reminds the Doctor of what the Silurians will do if they are able to launch the missiles . The Doctor is unable to find anything else harmful but less lethal , and regretfully begins to connect the gas containers to a central air pump . The Doctor is discovered by Sauvix before he can turn the pump on . Preston grabs a gun , but is killed by Sauvix ; Bulic sprays Sauvix with the gas , killing him . As the Silurians prepare to fire the missiles , the Doctor feeds the gas into the ventilation system . Bulic stays in the chemical store to ensure that the gas keeps flowing , while the Doctor and his companions leave for the bridge to try to stop the Silurians . Scibus activates the missiles as the Sea Devils begin to collapse from the gas , and the Doctor tells Tegan and Turlough to give the Silurians oxygen to keep them alive . The Doctor , aided by Vorshak , tries to stop the missiles by linking himself into the equipment as the sync operator . The Doctor succeeds , but Vorshak is killed by Icthar . Then Icthar is killed by Turlough . Finally , it is all over . The Doctor , his companions , and Bulic are the only survivors . The Doctor is left in despair for both the base ' s personnel and the Silurians , regretfully pondering , " There should have been another way . " Contents : Home video and audio releases . CD release . A CD of the original television soundtrack was released by BBC Audio in January 2008 , with linking narration by Janet Fielding .