Line Of Duty: Millions set to tune in for finale - but will H finally be unmasked? *** WARNING: THIS ARTICLE CONTAINS SPOILERS FOR THE LATEST EPISODE OF LINE OF DUTY, SEASON SIX, EPISODE SIX. DO NOT CONTINUE READING IF YOU ARE NOT UP TO DATE. YOU HAVE BEEN WARNED *** It's the big question the nation wants answered: No, not how Boris Johnson really refurbished his flat (that's second on the list of big questions), but who is "H", or "the fourth man/woman", as H is now known. On Sunday evening, a large proportion of the nation will be glued to their TV sets, hoping to have the H question and many more loose ends tied up in the final episode of the latest series of