DRAMA The Doctor, wearing sonic sunglasses and standing in an empty lecture hall, is mystified by a personal visit from the Pope. "Why would you do that?" he enquires, not altogether respectfully. He learns of an ancient document called the Veritas that's contained in a Vatican library, and of the new translation that's been posted onine. And the problem? Those who have read it have all taken their own lives. Can the Doctor solve the riddle - and survive?

An elegant pre-credits feint sets the tone for a typically classy mind-bender from outgoing showrunner Steven Moffat. As you'd expect, it doesn't neglect the funny (a papal audience for Bill plus ever-fretful Nardole). Otherwise this is a dark and rich existential workout, taking The Ring, The Name of the Rose and The Matrix as its reference points, and even Missy the minx (Michelle Gomez) has a subdued air.

An audacious two tales for the price of one, Extremis flits between Rome, Cern, Washington and a far-off world. It shows a writer in calm control of his material, and Peter Capaldi in private agonies as the careworn Doctor.