3:00PM, Oct 30, 2009
David Tennant reckons the next Doctor Who special could be the scariest ever.
The episode, titled The Waters Of Mars, sees the Doctor visit a human colony on the red planet.
Captain of the base is the strong-willed Adelaide Brooke (Lindsay Duncan), who works with the Doctor to save her crew from a terrifying watery threat.
Favourite creatures The Ood also return to warn the 10th Doctor that his "song is about to end," in an episode full of portent and prophesy.
"It tells a different story, it's a long time before the Doctor takes control," said David, who is set to leave the role at the end of this year.
"It's part of the story we have to tell to go where we're going."
Departing show boss Russell T. Davies described the story as "intense", adding: "The Doctor knows he's running towards his own end. It's a complicated story. Frankly it's very intelligent.
"This story shows why the Doctor travels with human companions."
Russell went on to describe David's two-part swan song, The End Of Time, as "magnificent".
The episode will see the Time Lord face his end as The Master (John Simm) returns for revenge.
"We tell a big old farewell story," said David "and then hand it over in rude health."
He added that he "can't wait" to watch the fifth series in 2010, which will see Matt Smith at the helm of a re-designed Tardis, with a brand new sonic screwdriver in hand.
But the actor maintained that he is sad to bid farewell to the 10th Doctor: "It was an incredible experience and something I will be forever proud of."
Doctor Who: The Waters Of Mars will air on Sun 15 Nov at 7pm on BBC1.
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