This is a Doctor Who series 4 spoiler with a sting in its tail – as such, tread carefully, and if you see any blank space, left click your mouse and drag it to select the invisible text.
Firstly, you may have heard that Donna is left to rely on former companions Rose Tyler, Martha Jones and Captain Jack, as well as Sarah Jane, when the Doctor mysteriously vanishes.
However, that one’s just for starters! In the Steven Moffat tale:
* There will be a character called “Lux” who helps the Doctor on an expedition to uncover the secrets of an abandoned library.
*Some new cast for the Sontaran 2 parter – Eleanor Matsuura (Jo), Ryan Sampson (Luke Rattigan), Rupert Holiday Evans (Colonel Mace), Bridget Hodson (Captain Price), Clive Standen (Harris), Wesley Theobald (Private Steve Gray)
The rest of these snippets are speculation and rumour:
*The actor playing Colonel Mace (Sontaran 2-parter) is telling people that he is the “new Brigadier”
*The Master will be back and played by John Simm but this is probably in a flashback.
*Rose will be in a relationship with someone
*Noel Clarke was asked if he will return a Mickey , the answer he gave suggested he might come back.
The last of these was first mooted several months ago, before Series 3 finished, so it will be interesting to see if Clarke does reprise his role.
Incidentally, I found this summary of whovian spoilers via the Doctor Who Insania blog