The BBC has released the synopsis for Episode 9 of the current series, Flatline.

Guest starring Christopher Fairbank, the episode has been written by Jamie Mathieson, directed by Douglas MacKinnon and airs on BBC One on Saturday 18th October at 8:25pm.

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.

New series, new Doctor, new adventures. Click here for all the latest on Series 8!