From the crash of Air France flight 447 between Rio and Paris into the Atlantic in 2009, to the Germanwings flight 9525 crash in the Alps in 2015, the French investigators of the BEA (Bureau of Enquiry and Analysis for Civil Aviation Safety) are called upon worldwide to determine the causes of air accidents. Line planes, helicopters, ultra-lights: BEA is investigating everything that flies. For the first time, they have allowed cameras to film their often confidential work. This documentary meets technicians and meteorologists, even ophthalmologists and acousticians, who are able to determine the causes of an accident from detailed details. It also follows the two-year search and recovery effort for an aircraft engine that went missing over the Greenland Ice Sheet.