Horizon tells the inside story of the search for Malaysia Airlines flight MH370. With access to the key players on the frontline in the southern Indian Ocean and the British satellite engineers who tracked the plane's final hours, Horizon breaks open the biggest mystery in aviation history. The film reveals how MH370 disappeared in a radar blind spot; what investigators believe happened to the aircraft in its last minutes; and how the area in which it could be found is still to be searched. Plus Horizon examines the new technologies, like black box streaming and enhanced air traffic surveillance, that mean an airliner should never vanish without trace again.