1x4 - Lost Signs

In a matter of moments, Manon deciphers what army specialists couldn't in months:"12 August 2007" and "We are their children." That same evening, Manon is kidnapped by a man with white hair. Laure and Xavier, who has been released from prison, visit Manon's hospitalized father, Lorenzo, who has a scar on his forearm identical to one another missing person had. This scar appeared when, as a child, Lorenzo was traveling from Paris to Marseille on Flight 173 -- the same plane that had vanished from radar screen for more than 20 minutes on June 17, 1980. What happened on that flight?