'The Waters of Mars' (Story Code 4.16) by Phil Ford and Russell T Davies

“Water is patient, Adelaide. Water just waits. It wears down the clifftops, the mountains, the whole of the world. Water always wins.” – The Doctor

When the TARDIS lands on Mars, the Doctor wastes no time in donning a space suit and heading outside to explore. However, his delight at seeing a man-made complex comprised of interlinking domes situated in a nearby crater is rudely interrupted when he finds himself held at gunpoint by a diminutive robot. Escorted to the base, the Doctor is introduced to the station’s no-nonsense captain, Adelaide Brooke, and her crew: Deputy Ed Gold, Doctor Tarak Ital, Nurse Yuri Kerenski, geologist Mia Bennett, Senior Technician Steffi Ehrlick and Junior Technician Roman Groom, who operates their robot, Gadget, by remote control. Learning that he has arrived in Bowie Base One, located in the Gusev Crater, the Doctor becomes excited at meeting the first off-world colonists in human history; however, his knowledge of history carries a burden, because he also knows that the personnel are destined to die in a nuclear explosion later that day, a blast that completely obliterates the base, its cause unknown – the Doctor has no choice but to leave... Elsewhere, in the Bio-Dome, agronomists Maggie Cain and Andy Stone work on their first harvest. Washing a freshly dug carrot under a tap Andy takes a bite of the first vegetable to be grown off-world – and then falls to his knees shaking uncontrollably. As Maggie goes to help her colleague she catches a glimpse of Andy’s face, now hideously cracked and bloated by excess hydration… After hearing Andy’s strange growls over the communications system and seeing the lights go out on the Bio-Dome, Adelaide forces the Doctor to join her as she sets off with Tarak and Gadget to investigate. Finding Maggie unconscious in one of the tunnels, Tarak calls on Yuri to take her back to the Medical Dome while he carries on with the Doctor and Adelaide; passing through the airlock, the group split up to search for Andy… Back in the Med-Dome, Yuri listens to a message from home, unaware that Maggie has now begun to transform behind him; when Yuri finally turns and sees Maggie’s bloated face, water coursing from her body, he immediately contacts the captain to inform her of his colleague’s transformation; ever practical, Adelaide instructs her team not to drink any water. After reactivating the Bio-Dome’s lights with his sonic screwdriver, the Doctor accompanies Adelaide as they make their way through the vegetation; they soon discover that Andy has overpowered Tarak and is now taking him over, sending jets of water from his hand into the doctor’s powerless body. The Doctor and Adelaide run for their lives, only just reaching the safety of an internal airlock before the two creatures can catch them; however, Andy and Tarak swiftly blast open the door with jets of water shot from their mouths, and the Doctor and Adelaide only just manage to escape with the aid of a lift from a seriously souped-up Gadget, courtesy of the Time Lord’s sonic screwdriver. As they reach the Central Dome, Adelaide informs the Doctor that they should be safe behind the stronger seals of the main airlocks; but the Doctor is unconvinced, knowing that the deadly water will soon find a way to reach them… Joining Yuri and Ed inside the Med-Dome, the Doctor and Adelaide attempt to talk with Maggie, but the woman only responds when the Time Lord addresses her in Ancient North Martian. After Adelaide informs the Doctor that the colonists have been obtaining their water supply from the huge glacier situated beneath Bowie Base, Ed surmises that a viral life form has been released: an alien creature perfectly at home in the human body, which comprises of sixty percent water. Ed advises Adelaide to initiate Action One: the evacuation of Bowie Base. As Steffi, Mia and Roman begin removing all records from the base’s computers the Doctor warns Adelaide that she is playing into water creature’s plans – exposure to a single drop of water could mean that any one of them is already infected, and escaping to Earth is just what the alien consciousness wants. As Adelaide leaves to inspect the ice field the Doctor knows he should just depart in the TARDIS, but his conscience gets the better of him and instead he runs after the captain. Back at the Med-Dome, Yuri grabs as many medical supplies as he can and then leaves; Maggie immediately begins blasting the airlock with water, overloading the door’s systems; she then lets out an unearthly wail that is heard by Andy and Tarak... Arriving in the Water Plant, the Doctor ponders on whether The Flood drove the Ice Warriors from Mars. When Adelaide pushes the Doctor to explain how he knows so much about their situation, the Time Lord unwillingly reveals that the captain and her crew are caught in a pivotal event in time – and that Adelaide herself is extremely important to history. His comment causes Adelaide to recall an incident when the Earth was stolen several years ago: a Dalek flew up to her bedroom window and saw her, but instead of exterminating her, the creature actually left her alive... The Doctor deduces that somehow the Dalek sensed that Adelaide was a fixed point in time, a pivotal link in humanity’s history: in thirty years time Adelaide’s granddaughter, Susie Fontana Brooke, will become the pilot of the first lightspeed ship to Proxima Centauri; her descendants will continue to travel out across the stars, encountering new worlds and cultures, even creating new species by interbreeding with alien races. Checking Andy’s maintenance records the Doctor and Adelaide learn that a single water filter failed – all that was needed to allow The Flood access to the base. Back in the Control Room, Mia, Steffi, Roman and Yuri continue packing supplies while Ed prepares the space shuttle for launch. Adelaide offers the Doctor the chance to leave the base, but as the Time Lord prepares to depart Ed discovers that Andy and Tarak have climbed up inside the base’s maintenance tunnels – and now standing right above them inside the infrastructure of the Central Dome’s roof. As the two creatures begin blasting the dome’s roof with powerful jets of water, Adelaide and her team frantically grab everything they need for the journey to Earth. The Doctor finally decides to leave, only to find the main airlock still locked. When Adelaide’s voice comes over the comm system demanding that the Doctor tell what he knows of her future the Time Lord realises he has no option, and he tells the captain that she will activate Action Five, the activation of the nuclear device at the centre of the base. However, not only will Adelaide’s actions burn The Flood, but her death will also create the future, by inspiring Susie to take up a career that will take humanity out into space. Unlocking the main airlock for the Doctor, Adelaide then rejoins her crew – just as Andy and Tarak succeed in breaking through the roof. As water pours down around them Adelaide and her crew run for safety, but Steffi is trapped by a shower of contaminated water and forced to lock herself inside the video alcove. Separated from the others in her final moments, Steffi plays a recording of her children as the water bursts through and infects her… Making his way across the Martian surface towards the TARDIS the Doctor hears the terrible events inside the base over his comm: Roman has been infected by a drop of water, and he too transforms into The Flood; forced to abandon their colleague, Adelaide, Mia and Yuri race for the shuttle; meanwhile, Ed completes final checks for the shuttle’s lift-off – only to be blasted by a stream of water as Maggie enters the flight deck. Knowing he only has seconds left until he is taken over, Ed informs Adelaide of his situation and then activates the shuttle’s self-destruct mechanism – the ship explodes in a gigantic explosion, throwing Adelaide, Mia and Yuri to the floor as debris rains down all around them. Out on the planet surface, the Doctor staggers back to his feet and hears his own voice inside his head, repeating how he is the last of the Time Lords. Suddenly realising the implications of what this actually means, the Doctor rushes back to the base to rejoin Adelaide, Yuri and Mia inside the Central Dome. Instantly taking charge, the Doctor instructs everyone to seal the cracks in the walls and open the emergency oxygen supplies, before excitedly explaining his reason for returning: he cannot be stopped because he knows he won’t die until someone knocks four times – but the Doctor’s smile immediately falls when Andy appears outside the airlock and starts banging on the door. At three knocks the Doctor electrifies the door, repelling the water-soaked Andy; he then vows to save Adelaide, Yuri and Mia: as the last of the Time Lords, the Laws of Time no longer apply to him – not only is he going to beat the water, but he will beat Time itself! Elsewhere, Maggie reaches the lower levels and lets out a terrifying screech that shatters the ice below. When Adelaide activates the base’s self-destruct procedure the Doctor uses Roman’s remote control equipment to send Gadget rocketing across the Martian surface towards the TARDIS. Meanwhile, Andy, Tarak, Steffi and Maggie howl in unison of their impending triumph, unaware that they, the base and the ice below it are all about to be obliterated. Using Gadget to activate the TARDIS’ controls the Doctor transports his ship inside the control room. The self-destruct countdown finally reaches zero, and Bowie Base One and the Flood are completely atomised in a massive nuclear explosion. Escaping the blast in the nick of time in the TARDIS, the Doctor takes Adelaide, Yuri, Mia and a now-powerless Gadget back to Earth, materialising just outside Adelaide’s town house. The Doctor is unbearably pleased with himself, but his newfound arrogance just horrifies the others. Mia freaks out and runs off in tears, so Adelaide sends Yuri to go and look after her. Adelaide is concerned that by saving her life the Doctor may have changed the course of time, an action that will prevent her granddaughter from ever fulfilling her pivotal role in history; the Doctor’s smug reassurance that this cannot happen because she is a fixed point in time fails to convince Adelaide, and she is appalled at his declaration of being “The Time Lord Victorious”. With her face set in grim determination, Adelaide enters her house and upholsters her weapon… Hearing a gunshot the Doctor spins round, his eyes widening in horror as Adelaide’s suicide alters the timeline enough to ensure that her granddaughter’s destiny is fulfilled. As the implications of his actions sink in, the Doctor realises that he has gone too far – he then falls to his knees and sees a vision of Ood Sigma standing before him. Knowing that his story is about to end, the Doctor enters the TARDIS and departs – and then the Cloister Bell begins to toll…

David Tennant (The Doctor), Lindsay Duncan (Captain Adelaide Brooke), Peter O’Brien (Deputy Captain Edward ‘Ed’ Gold), Aleksandar Mikic (Nurse Yuri Kerenski), Gemma Chan (Mia Bennett), Sharon Duncan-Brewster (Maggie Cain), Chook Sibtain (Doctor Tarak Ital), Alan Ruscoe (Andy Stone), Cosima Shaw (Senior Technician Steffi Ehrlich), Michael Goldsmith (Junior Technician Roman Groom), Lily Bevan (Emily), Max Bollinger (Mikhail), Charlie De’Ath (Adelaide’s Father), Rachel Fewell (Young Adelaide), Anouska Strahnz (Ulrika Ehrlich), Zofia Strahnz (Lisette Ehrlich), Nicholas Briggs (Voice of Gadget), Paul Kasey (Ood Sigma)

Directed by Graeme Harper
Produced by Nikki Wilson
Executive Producers Russell T. Davies and Julie Gardner
A BBC Wales production

TX (BBC 1 & BBC HD):
15th November 2009 @ 7.00 pm

Notes:
*Featuring the Tenth Doctor

*This hour-long special was also simulcast on the BBC's HD channel

*This special had an on-screen dedication to the memory of former 'Doctor Who' producer Barry Letts, who died in October 2009