The first episode of the new series starts at the Royal Hope Hospital, where the Doctor's new assistant Martha (Freema Agyeman) is a medical student.
Looks like Martha's found something that's not quite right, but what could it be?
Maybe she'll have more luck working it out when she teams up with the Doctor (David Tennant).
Then again.....here they are making a run for it through the hospital corridors. But what are they running from?
Surely it's not this slightly nutty-looking old lady, Florence Finnigan (Anne Reid)?
She might look all sweet and innocent, but is she all she seems?
The Doctor certainly doesn't look too happy anymore.....
Uh-oh, he's been caught. But who, or what, is that sinister-looking character behind him?
Whatever it is, it's done something to take the Doctor by surprise!
Is that Florence who's walked in on them? Maybe she'll try to help......
Oh, hang on.... she doesn't look that friendly anymore does she?
Thank goodness the hospital consultant, Mr Stoker (Roy Marsden), seems to be keeping an eye on things.
But he forgot to look over his shoulder! Now the sinister characters in black have got him too.
What on earth's going on? You'll have to wait to catch the full episode on BBC1, on Saturday 31 March, to find out.