One of the Doctor's oldest enemies - the Cybermen - are back!
Newsround's Tim Masters ventures onto the Doctor Who set in Wales - and finds the silver giants trying to keep warm!
Watch our Cyberman behind-the-scenes film on the Newsround Player - click on the purple box on the top right.
Scrunch, scrunch, scrunch.
Huge silver boots are moving through
the first snowfall of winter on an industrial estate outside Newport.
A troop of Cybermen have turned up ready for filming in a warehouse on this freezing November morning - and they are all wearing dressing gowns!
This is where some of the key scenes are being filmed for Doctor Who episodes five and six, The Rise of the Cybermen and The Age of Steel.
As I arrive the set dressers are still hard at work putting the final touches to the Cyber control room.
In one corner, a carpenter is banging a length of silver tubing into place. Behind me, the Cyber Controller's massive chair is being pushed into position.
And on the floor, 10 Cyberheads are lined up ready for the day's filming. They look extra creepy with no-one wearing them. And one of them has a brain inside. Yeeuch!
This is the helmet of the Cyber Controller who's played by actor Paul Kasey. I find him outside grabbing a quick cup of coffee in his bulky costume and dressing gown.
So what's it like playing a Cyberman?
"It's very exciting. Everything that has been filmed so far is fantastic. They are very scary."
How long does it take to get into the costume?
"It started off at half and hour but I've got it down to about 20 minutes as we've been doing it a couple of weeks now."
And the most important question of all: how does a Cyberman go to the toilet?
"There are special holes in the suit - once the special Cyberpants are taken off!"
Paul's no stranger to being a Doctor Who monster. In the last series he played an Auton, a tree person, a Slitheen and the android Zu-Zana.
'Hearts of steel'
Back on set, the man who provides the Cyberman voices is getting warmed up.
"Hell-o Mum! Ex-ter-min-ate!" says Nick Briggs using his ring modulator machine to change the sound of his voice.
Nick is also the voice of the Daleks, but he sees an important difference when it comes to the Cyberman.
"The difference is that the Daleks are absolutely bonkers! They are really cross about everything, while the Cybermen have no emotions. Their hearts are made of steel and they all sound exactly the same."
The Cyber Control Room has a huge amount of detail. There are banks of monitor screens and clocks on the wall showing the times in Tokyo, Moscow, Paris and New York. Everything belongs to "Cybus Industries".
Suddenly, David Tennant and Billie Piper arrive on set, and everyone gets into their places.
The room is crammed with people that you don't see on camera. It takes a lot of people to make Doctor Who.
There are a couple of rehearsals, and then the Cyberman actors remove their dressing gowns and their metal heads are clamped into place.
The assistant director shouts: "Quiet please!" and the cameras roll.
It might be snowing outside, but watching the Cybermen in action is pretty chilling stuff as well.
The second part of the Cyberman story, The Age of Steel, is on Saturday at 6.35pm on BBC One. Watch our Cyberman behind-the-scenes film on the Newsround Player - click on the purple box on the top right.