What happened on board the Dubai-Paris flight before it crashed in the Alpine massif? A technician at the BEA, the authority responsible for safety investigations in civil aviation, Mathieu Vasseur is propelled as the chief investigator into an unprecedented air disaster. Piloting error? Technical failure? Terrorist act? The careful analysis of the black boxes will push Mathieu to conduct his own investigation in secret. He does not yet know how far his quest for truth will take him.