Yes. that's right the Cybermen are back!

And it looks like the metal monsters will be taking over central London and doing some very strange things to St Pauls Casthdral in Saturday's episode of Doctor Who - Dark Water.

The Cybermen and The Doctor, Crouch End actor Peter Capaldi, were spotted filming at the landmark earlier this year, in scenes reminiscent of the iconic 1968 episode, The Invasion, starring Patrick Troughton.

Dark Water is the first episode in a two-part story written by Steven Moffat for the finale of season eight.

But what does the dark refer to? Could it be to companion Clara flipping over to the dark side? The trailer for the episode features her emerging from smoke and flames to confront the Doctor.

"Do I have your attention?," she says holding up a key. "You will never step inside your Tardis again."

She goes on to say "Time can be rewritten. I’m not Clara Oswald. Clara Oswald has never existed."

The episode also looks set to fianlly reveal more about the mysterious Missy, aka the Gatekeeper of the Nethersphere, played by Michelle Gomez.

The episode also stars Jenna Coleman, Samuel Anderson, Chris Addison, Jemma Redgrave and Ingrid Oliver.