A prisoner on Death Row in Victorian London reveals that the Doctor has a secret-one that will be revealed at his grave on Trenzalore. The Paternoster gang-who psychically contact River (or at least, her post-death library copy) and Clara, via a psychic conference call-reveal.However, the gang apart from River and Clara are soon captured by the Great Intelligence and his latest henchmen-the Whispermen-and taken to Trenzalore itself.
The Doctor relucantly travels to Trenzalore to rescue them, but it’s clar that what’s happened her has happened already-there are graveyards, and a giant TARDIS, presumabely the Doctor’s own headstone-presumably containing the Doctor’s remains.
And this tomb-which the Great Intelligence wants to enter-can only be opened with the Doctor’s name-his greatest secret. Of course he doesn’t want to say it-it is pretty much the point of the title-but River says it for him, opening the doors.
Inside is not quite a body, but a Timestream-the sum of the Doctor’s timeline, represented as a form of energy-and the Great Intelligence enters it-messing everything up, killing or thwarting the Doctor at various points during his lives, causing all the good thing’s he’s done to start to come undone. It causes the Eleventh Doctor considerable agony, as his whole life/lives are unraveling.
However, there’s one thing that can be done. Clara enters the Time stream to save the Doctor-and she does so, on many occasions. The previous Claras he encountered before were actually splinters of her that had been born to help the Doctor, created by the original Clara.
She helps the first Doctor select a TARDIS when he escapes Gallifrey for the first time.
She helps out the Third while he’s driving Bessie. She even has something to do with a strange cliffhanger on Iceworld (With an Ace-style look to boot!)
And of course as Oswin and the Snowmen Clara, she helps the current incarnation.
However, even though he’s been saved, the Doctor realizes that this could be fatal to Clara. He jumps into his own timestream, rescuing her. However, before he leaves, they both spot an unusual, bearded man. The Doctor reveals that this is also him, but also not him-an incarnation he’s been trying very, very hard to forget, that broke the promise of being the Doctor and saving people…his ‘secret’ is not his name, but his own ashamed past.
The Doctor Who Fought in the Time War-the Doctor’s darkest hour.
That’s John Hurt of “Alien” “Harry Potter” “Elephant Man” and “Indiana Jones” fame among others, as the War Doctor.