Watch a preview for the next episode of Doctor Who, "Before The Flood."
Tonight's episode already aired in the UK, with a fan apparently uploading the preview (above) to YouTube.
Doctor Who airs on BBCA Saturdays at 9pm ET starring Peter Capaldi and Jenna Coleman.
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?