Every BBC One's Line of Duty theory ahead of nail-biting finale WARNING POTENTIAL LINE OF DUTY SPOILERS BELOW Subscribe When you subscribe we will use the information you provide to send you these newsletters. Your information will be used in accordance with ourPrivacy Notice. Thank you for subscribingWe have more newslettersShow meSee ourprivacy notice As the hugely popular Line of Duty series six draws to an end - desperate fans have been frantically trying to work out what's in store. Millions of viewers are hoping that H will finally be unmasked when the show airs on Sunday, May 2, spanning nine years.