Doctor Who Series 9 - Before The Flood synopsis

The BBC have released the official synopsis for Episode 4 of Doctor Who Series 9, Before The Flood, check it out below.

On a remote Army outpost, a fearsome alien warlord - the Fisher King - sets in motion a twisted plan to ensure his own survival. The ripples will be felt around the universe. Is this chain of events inevitable? And can the Doctor do the unthinkable?

Under The Lake airs 8.25pm, Oct 10 on BBC One. Read the Episode Guide to Doctor Who Series 9 HERE.