Gridlock ( TV story ) Gridlock was the third episode of the third series of BBC Wales " Doctor Who " . It marked the death of the Face of Boe and his final words to the Tenth Doctor . It also saw the first televised appearance of the Macra since their introduction in 1967 ' s " The Macra Terror " . The Doctor and Martha Jones were separated for most of the story . Synopsis . The Tenth Doctor takes Martha Jones to New Earth , in the far future , only to find that the entire city has become a deadly trap . Plot . American newscaster Sally Calypso gives the daily travel news to all the cars . Ma and Pa are seated in one of the camper - vans . They call the police for help as they are apparently attacked by something from outside . They are placed on hold by the police computer system , and scream as their car is torn apart . The Tenth Doctor offers Martha one trip into the future , to visit another planet . She asks if he can take her to his home planet , and speculates as to its beauty . He describes Gallifrey ' s Citadel , mountains , orange sky and other features as if they still existed , but claims he does not want to go home . Instead , he takes her to the year five billion and fifty three , into a dark alleyway where it is rain ing , and introduces her to New New York in New Earth . The Doctor repeats some things he told Rose the last time he had visited the planet . Martha becomes slightly upset when she realises she is being taken to the same place the Doctor took Rose , and mutters " Ever heard the word rebound " . Meanwhile , the Face of Boe sits in a room with Novice Hame . He tells her to find the Doctor before it is too late . She takes out a gun and leaves . The Doctor and Martha are in a run - down street . Three pharmacists open their market stands and try to sell the Doctor and Martha patches that dispense " moods " . The Doctor is angry , but intrigued when a young girl buys a Forget patch after losing her parents to " the Motorway " . Suddenly , a young couple armed with guns grab Martha and haul her away , subduing her with a patch inducing Sleep . The Doctor chases them but they escape in their car . The Doctor asks the pharmacists for directions to the Motorway ; they comply , but warn him that he may never see Martha again . He tells them to find alternative employment as he promises to shut down their enterprises by that very evening . Martha wakes up and grabs a gun , only to learn it is a fake . Her kidnappers introduce themselves as Milo and Cheen . Cheen says she is pregnant . Milo explains they only wanted her so they could get on the Fast Lane , which requires three adult passengers . They say they can drop her off when they reach their destination — in six years . The Doctor arrives at the Motorway , where he discovers thousands of " Volkswagen " - like hover vans in a traffic jam . He starts to cough and choke from the fumes . A cat person invites him into his car , introducing himself as Thomas Kincade Brannigan and his human wife as Valerie . Their kittens , two months old , have never seen sunlight or trod on ground . The Brannigans themselves have been driving for twelve years , and have travelled only five miles . As Milo , Cheen and Martha head for the Fast Lane , the Doctor calls the police but is put on hold . Brannigan speaks to some old friends , the Cassini " sisters " ( a same - sex married couple ) , who identify the one car from Pharmacytown that has gone to the Fast Lane . The Doctor learns that some people haven ' t left their cars in upwards of twenty years . Milo , Cheen and Martha are dropping down to the Fast Lane , but there are strange noises . Cheen tells Martha of stories about cars disappearing but Milo insists they only hear the ventilation shafts . Brannigan and Valerie refuse to go to the Fast Lane , fearing for the safety of their kittens . The Doctor asks whether they or the Cassinis have ever seen any authorities . The Cassinis reluctantly admit they have not seen any police or ambulances in 23 years of driving . The Doctor believes that the people have been trapped in the under - city and abandoned . Making his own way toward Martha , he opens the shaft on the floor of the car and drops down to the car below . He then moves through several cars , opening the roofs with his sonic screwdriver and continuing through the floor to the car below . In this fashion he meets several characters including hippies , a Bertie Wooster - like business man and a nudist couple . Martha ' s car enters the Fast Lane , but the exits are all closed . A nearby cat driver tells him to escape to the slow lanes above , but Milo does not believe in the danger until he hears the other driver ' s screams . Meanwhile Novice Hame reaches Brannigan ' s car and demands to know where the Doctor is . The Doctor reaches the lower levels , just above the Fast Lane . He clears the fog to discover what ' s down there : the Macra . The Doctor explains to the car ' s driver that the Macra feed upon toxic gas . Once in history they had built an empire using human slave s to mine gas to feed them , but have since devolved into hungry non - sentient beasts . As Martha ' s van races along the Fast Lane , the Macras ' huge claws attempt to crush it . Reasoning that the light and motion of the vehicle attract the Macra , Martha has Milo turn off the power . It works , but they only have eight minutes of air . Novice Hame makes it to the car that the Doctor is in . She tells him how she has repented her sins under " his " guidance , and teleports the Doctor against his will to the upper city . She explains that everyone in the upper city , and indeed the whole surface level of New Earth , died because of a virus in the Pharmacists ' Bliss drug , but the under city was sealed off and Hame was protected by " him " . The citizens in the undercity have not been betrayed and abandoned ; they have been saved . Hearing a familiar telepathic voice , the Doctor runs to meet the Face of Boe . Hame says the Face has wired himself to the system to keep the lower levels functioning , but they are unable to free the people there . The Face of Boe asks the Doctor to save the people of the Motorway . Milo ' s car is running out of air and , despite Milo and Cheen ' s doubts , Martha says the Doctor will think of something . Milo starts the power up again , giving them air but exposing them to the Macras ' grasp . As the car races along , they are briefly caught by one of the claws , but are knocked free by another Macra . The Doctor asks Hame to help him restore power , but there is not enough . The Face of Boe , in one last act of self - sacrifice , gives even more of his " life force " to power the equipment . The Doctor pulls a lever , opening the seal at the top of the motorway . The sunlight beams in , and the Doctor broadcasts to the motorists , telling them to drive upwards and out . This clears the way for Milo ' s car to escape from the Macra . Meanwhile Hame cries out as the Face of Boe ' s glass begins to shatter . Martha arrives at the Senate building where she sees human skeletons , and meets the dying Face of Boe , sprawled out on the ground . The Doctor urges him to live , since ( as Boe says ) the two of them are each the last of their kind ; but the Face responds , " Everything has its time " . As promised , he whispers his great secret to the Doctor — " Know this , Time Lord ; You are not alone " — before passing away . An expression of shock and disbelief crosses the Doctor ' s face as Hame weeps . Martha and the Doctor arrive back at the alleyway . The Pharmacists are gone . Martha asks what the Face meant , and whether she is why the Doctor is not alone . The Doctor shakes his head ; he does not want to talk about Boe ' s words , but Martha refuses to move until the Doctor tells her the truth . The Doctor admits he is the last of his kind , explains about the Last Great Time War and the Dalek s , and then goes on to describe Gallifrey . Far above the slums , the over - city thrives with the newly freed motorists . The sun sets orange over New New York . Story notes . Filming locations . The scenes between the Face of Boe , Novice Hame and the Doctor were filmed at the Temple of Peace in Wales .