Midnight ( TV story ) Midnight was the tenth episode of the fourth series of the BBC Wales version of " Doctor Who " . It was the first " companion - lite " televised " Doctor Who " story . It also featured the third abrupt cameo of Billie Piper as Rose Tyler in the series before her role in the seasonal arc fully unfolded . In production terms , it was the first episode of " Doctor Who " to be filmed primarily in narrative order since the practice was abandoned around the time Jon Pertwee began portraying the Third Doctor . It was the only story in which the antagonist was never even partially glimpsed , leaving the threat to be realised by the actors and the sound editor s . It was also the second episode of 2008 to guest star the child of an actor who had played the Doctor : David Troughton as Professor Hobbes , his father having played the Second Doctor . The sound team of Tim Ricketts , Paul McFadden , Paul Jefferies and Julian Howarth shared a Royal Television Society Award and a Welsh BAFTA for their work on this episode . Synopsis . The Tenth Doctor and Donna Noble go to the leisure planet of Midnight for a simple , relaxing holiday . However , life with the Doctor can never be that simple , and things go horribly wrong for the Doctor when he decides to go off on an bus trip to see the Sapphire Waterfall , starting with the bus shutting down . When a mysterious entity infiltrates the shuttle bus , no one is to be trusted . Not even the Doctor himself . . . Plot . The Tenth Doctor and Donna spend some leisure time on the crystalline planet Midnight , whose crust is composed of diamonds . Though stunning and visually unique , the planet is also dangerous . The sun it orbits emits phenomenally lethal X - tonic radiation and there is no atmosphere ; exposure to the surface for even a split second would result in the unfortunate person being instantly vaporised . Donna receives a call from the Doctor , who wants her to go on a trip to see the Sapphire Waterfall , but she insists that she ' d prefer relaxing at the spa and sunbathing . However , the Doctor warns her to be careful because of the X - tonic radiation . Paying him no mind , since the glass she ' s under is fifteen feet thick , Donna agrees to try out the anti - gravity restaurant ( with bibs ) once he gets back . Despite her warning him to be careful , the Doctor jinxes himself : " Taking a bus full of strangers across a diamond planet called ' Midnight ' , what could possibly go wrong ? " He boards a shuttle bus ride to the Sapphire Waterfall . Other passengers include the Cane family ( Val , Biff , and their bored teenage son Jethro ) ; Professor Hobbes , who is investigating the waterfall ; his assistant Dee Dee Blasco ; and recently - divorced businesswoman Sky Silvestry . Before they take off , the driver informs them they are taking a different route to the Waterfall Palace because of a diamond fall on the regular path . For the long journey to their destination , the hostess activates the prerendered entertainment for passengers , consisting of several annoying television programs . Most of the passengers find the entertainment to be rather irritating , rather than pleasing . The Doctor discreetly disables them with his sonic screwdriver ; most of them are thankful for the small mercy that they ' ve been granted . This forces the passengers to talk and get to know each other better . The Doctor has an amusing conversation with Biff and Val . Later , during the passengers ' meal time , the Doctor talks with Sky about travelling , remarking that he " had a friend who went to a different universe " ( Romana in E - Space or Rose in Pete ' s World . ) After the meal , the Doctor talks with Dee Dee about the lost moon of Poosh over coffee in the back ; Dee Dee wrote about it and was selected as by Hobbes as his assistant . However , Dee Dee admits Hobbes uses her as a errand girl , rather than a proper assistant . Smiling , the Doctor asks whether or not the lost moon was found . Laughing , Dee Dee tells him no ; the Doctor suggests that finding the moon might be her great discovery some day . They toast glasses . Later , Prof . Hobbes , who has been studying Midnight , presents a slide - show about it ; he considers himself an expert because no one has ever researched it before , and that essentially nothing is known about Midnight . X - tonic radiation would vaporise any known form of life in seconds , so Midnight has been totally undisturbed for millennia . Hobbes notes even the Leisure Palace was prefabricated and dropped in from orbit . Jethro points out , to the disapproval of his parents , no one can really know anything about the planet , or whether or not life resides there . Hobbes agrees with him ; no one has ever really set foot on Midnight , and no one has any real idea what is on or underneath the surface . Anything could be out there . Suddenly the shuttle stops , everyone guesses that they must be there . However , Professor Hobbes tells them that he ' s been on the trip twelve times ; they never stop and it ' s too early for them to have arrived . Curious , the Doctor uses his psychic paper to pose as someone from the Leisure Palace insurance company . He talks to driver Joe and mechanic Claude , learning that there is nothing wrong with Crusader 50 ' s systems ; however , they are stopped . He convinces them to open the shutter to look outside as the landscape is beautiful . Mountains and cliffs and ridges , composed entirely of diamonds and sparkling in the white - blue X - tonic sun . Joe informs the Doctor that the path they ' re on is new and never been traversed ; they ' re the first ever to roam this part of Midnight . Suddenly , the mechanic points out at the landscape , having apparently seen movement . He dismisses it , but the Doctor seizes on it eagerly . Before Claude can elaborate , the X - tonic starts to overwhelm the cockpit ' s finitoglass windscreen and Joe closes the shutter . Right before it closes , Claude sees the movement again ; a shadow running towards the bus . Joe tells the Doctor that a rescue vehicle is on the way , and to keep quiet about things . The Doctor returns to the cabin , where the Hostess pushes past him to talk to the duo . Mrs . Silvestry asks him what ' s going on , prompting everyone to talk over themselves to ask him question . This leads them to start wondering about the amount of oxygen they have . However , the Doctor calls for silence and prompts Dee Dee , an expert on vehicles as her father is a mechanic , to explain ; the air is recycled , so they can breathe for years inside the bus without any worry . A few moments later , something begins knocking on the hull . Again , everyone panics , but the Doctor temporarily pacifies them as he listens to the knocks with his stethoscope . The knocking moves around the bus towards both doors , even testing one to see if it can open it . Biff knocks thrice on the door to prove the ship is sturdy ; the knocks repeats his pattern . Everyone freaks out as the Doctor knocks four times on the hull to confirm if there is something outside despite Hobbes ' attempts to make everyone believe nothing can be outside . However , everyone ignores him since they do not believe him and the knocking debunks that . The knocking moves around the shuttle , making its way towards Sky , who has become hysterical , remembering a past threat her partner made to her during the divorce . The knocking stops as a dent appears in the door Sky is next to . The lights fail and the shuttle is violently rocked . When the lights are restored , there is a working screen behind the Doctor , who turns away when he sees a singer on it , but it quickly turns to a muted video of Rose , who is shouting , " Doctor ! " No one notices . The hostess distributes torch es and everyone looks around to see if any are injured . Jethro notices the seats near Sky have been ripped off the floor and she is cowering in the corner . The hostess fails to contact the crew in the cabin , realises the main generator is down and opens the door to the driver cabin . Only X - tonic light can be seen , forcing her to close the door . The Doctor opens up a systems panel with his sonic screwdriver to examine it for any faults , but behind the face plate are several cut wires ; the driver ' s cabin has been ripped away , vaporising driver Joe and mechanic Claude . Jethro calls everyone ' s attention back to the cowering Sky , who hasn ' t moved a muscle ; the Doctor kneels next to her and tries conversing with her . Sky initially remains motionless , but is coaxed into turning around by the Doctor . Attempts to get her to speak cause her to start repeating what everyone else says . Deciding to test how well Sky can copy them , the Doctor says the square root of pi , becoming amazed she repeats every number without fail even when they were talking over each other . The Doctor speculates about what is happening and what will happen to Sky , believing the entity that was knocking on the hull has taken over her consciousness . The back up generator comes on and the Professor tries to have everyone calm down and be rational . However , Jethro and the Doctor notice that Sky is speaking simultaneously with Hobbes , and everyone else for that matter . The Doctor decides to test Sky by saying random terms , nonsense words and reciting the alphabet and abruptly stopping , with Sky perfectly copying him in perfect sync . The passengers contemplate throwing Sky outside , horrifying the Doctor , who thinks that the entity might be trying to learn . He tries to calm everyone down , however his attempt to take charge backfires as the passengers become suspicious of him , especially when he proves unwilling to reveal his real name or origin and admits to feeling a thrill from the situation . The passengers contemplate throwing him out too , if he gets in the way of them trying to save themselves . However , as the Doctor protests that they will need him to survive if the entity turns out to be malevolent , Sky stops repeating everyone and focuses solely on the Doctor . To try reasoning with the consciousness in Sky , the Doctor attempts to offer it help with finding a voice of its own without stealing his . However , when the Doctor asks the entity if it can agree with him , he has spoken after Sky . The Doctor is now repeating Sky ' s words , motionless and clearly strained as if fighting something . Most reason that it ' s the Doctor that is possessed now , as Sky can move again . However , the hostess and Dee Dee think this is just the next step : stealing the voice of another as the Doctor had predicted . The other passengers refuse to listen ( with Hobbes furiously telling Dee Dee that he considers her to be " average at best " ) to reason and decide to throw the Doctor out the nearest door , all the while being goaded on by Sky , who is strangely happy despite the madness going on . The Doctor shows minimal signs of resistance to being pulled towards a door by Biff and a reluctant Hobbes as Sky describes how the entity is insidious and gets inside the humans ' heads . However , the hostess realises that Sky is not talking in her own voice ; she uses two phrases the Doctor had used earlier ( " Molto bene " and " Allons - y " ) . The entity in Sky has stolen the Doctor ' s voice . " Sky " notices the hostess is not fooled by her performance and is fearful . To save the Doctor , the hostess sacrifices herself to drag the entity out of the bus and out into the X - tonic sunlight , vaporising them both . The Doctor slowly recovers from his paralysis ; Val tries defending herself by saying she knew it was Sky . He simply glares at her . The passengers wait for the rescue vehicle in a haunted silence . When the rescue bus finally comes for them , the Doctor asks " The hostess ; what was her name ? " . To their great shame and remorse , the passengers realise that they never asked the name of the woman who just saved them all . Back at the spa , the Doctor mournfully reunites with Donna . The two later discuss what happened with the Doctor still clueless over the origin of the creature , if it survived or how many more there may be . Either way , he intends to inform the Leisure Palace Company and have them leave Midnight behind , silently orbiting the X - tonic star once again . Donna can ' t fathom what the Doctor would be like without a voice . The Doctor tells her , " Molto bene " , with a smile . Donna copies him . Disturbed , the Doctor tells Donna not to do that , then looks away , clearly still haunted .