Two years after the devastating effects of The Reichenbach Fall, Dr John Watson has got on with his life. New horizons, romance and a comforting domestic future beckon; but, with London under threat of a huge terrorist attack, Sherlock Holmes is about to rise from the grave with all the theatricality that comes so naturally to him. It's what his best friend wanted more than anything, but for John Watson it might well be a case of 'be careful what you wish for'. If Sherlock thinks everything can be just as he left it though, he's in for a very big surprise. Written by BBC