It is the most important day in the history of Earth: the dawn of a new age of harmony or the start of its final war.
In the latest episode of the time-travelling drama, written by Chris Chibnall, The Doctor must face his most difficult challenge yet. It is a battle in which he cannot take sides and a day when nobody must die...
The Doctor is played by Matt Smith and Amy Pond is played by Karen Gillan.
Doctor Who is simulcast on the BBC HD channel – the BBC's High Definition channel, available through Freesat, Sky and Virgin Media.