Doctor Who S10 E04 Knock Knock

Doctor Who S10 E04 Knock Knock : Bill is moving in with some friends and they’ve found the perfect house! So what if it’s strangely cheap to rent, and the landlord is a little creepy? The wind blows, the floorboards creak and the Doctor thinks something is very wrong. What lurks in the strange tower at the heart of the building – and why can’t they find any way to enter it..?