The BBC has published the official synopsis for the ninth episode of Doctor Who‘s new season, titled ‘Flatline’.

Written by Jamie Mathieson, the episode airs on Saturday 18 October on BBC One and is described by Steven Moffat as “a horror story” and “a proper scary one”.

The synopsis reads: “Separated from the Doctor, Clara discovers a new menace from another dimension. But how do you hide when even the walls are no protection? With people to save and the Doctor trapped, Clara comes up against an enemy that exists beyond human perception.”

Season 8 continues this weekend on BBC One with ‘Kill the Moon’.

> Here’s everything we know so far about Season 8.

Are you looking forward to ‘Flatline’? Let us know below…