When an Underwater Base comes under attack, the Doctor and Clara must save the frightened crew and defeat an impossible threat. But what is behind these terrifying events? And can they really be haunted by ghosts?
Writer: Toby Whithouse
Director: Daniel O’Hara
Producer: Derek Ritchie
Cast: Peter Capaldi and Jenna Coleman
Guest cast: Colin McFarlane, Sophie Stone, Zaqi Ismail, Morven Christie, Arsher Ali, Steven Robertson, Paul Kaye.