7:20pm-8:10pm BST (18:20 GMT) « » « »
Featuring: Peter Capaldi, Matt Lucas, Pearl Mackie
London, 1814. The entire city has turned out for the biggest Frost Fair in decades. But beneath the frozen Thames, revellers are disappearing, snatched through the ice and pulled into the depths where a terrifying monster lurks. Will the Doctor and Bill stop the slaughter before they too are dragged into the icy waters?
Synopsis Source: BBC website schedule listing