Summer 1980. An airplane disappears from the radar screens somewhere between Paris and Marseille. Twenty years later, strange forms called Crop Circles appear in a cornfield. At the same time, Laure de Lestrade, who is about to sell her mother's house, discovers similar drawings in her school notebook. Coincidence? An assault, upsetting remarks, a stormy reunion with her family, a recent photo on the Internet of a woman with a strange resemblance to her mother, who vanished 20 years earlier -- all this intrigues her. What do these events all mean? Can her mother still be alive?
Lucas, the son of Erika and FranĂ§ois de Lestrade, Laure's half-brother and son of General de Lestrade, is almost kidnapped. Laure, his aunt, begins to wonder if there is a connection between the mysterious vanishings of several of her relatives. In each case, the few witnesses mention a man with white hair, a mesmeric look and a black car with smoked windows! Laure is upset by her boyfriend Xavier's suspicions about her father, General Guillaume de Lestrade. As the army deciphers an enigmatic number, 120807, in a Crop Circle, Laure is drawn to a protected site with an old algorithm and caught in a halo of blue light...
Abducted by hooded individuals, Laure finds herself face to face with her father, who tells her that he is in charge of the secret military "STAR program" which is investigating the Crop Circles. At the same time, Xavier claims he's just found a daze young amnesiac - whom Laure recognizes as her old boyfriend, Christopher, who had vanished 13 years earlier. FranĂ§ois de Lestrade has Xavier arrested on charges of kidnapping. Laure learns of the existence of a child named Manon, who is said to be able to read the Crop Circles. Meanwhile, army doctors conduct tests on Christopher in order to probe his memory. Under hypnosis, he writes down a single name: Manon.
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?
Laure learns that the scars are implants and that the first scientist to have identified them seems to have been his mother's physician, Professor Roger. At Roger's home, Laure only finds an abandoned house, once the scene of a terrible tragedy: when Dr. Roger apparently murdered his own family and fled. Laure breaks in to find canvases similar to the paintings of artist Gaston Denis, which hung in her family's chateau. The painter and Dr. Roger would seem to be one and the same person. Trailing the gallery owner exhibiting Denis's work, Laure comes to a remote farmhouse where she finds the black car with smoked windows. Suddenly, a man with white hair, Dr. Roger, the man behind the vanishings, looms up behind her...
Laure is found tied, gagged and locked into the cellar of the house. Roger again is on the run. Laure and Xavier learn that Irene, Laure's mother-in-law, has a Denis painting and knew Dr. Roger. Xavier finds a sort of will left by Roger addressed to Laure: a video showing an implant extraction performed by Dr. Roger himself; and a tape of an extraterrestrial announcing he is coming to earth to "take back the children." Laure wants to see Lorenzo again. Erika, Laure's sister-in-law, admits her secret: she had an affair with Lorenzo and fears her husband might find out. Laure decides to hide him. When Erika comes to see Lorenzo with her son, Lucas immediately calls Lorenzo, "Papa." Though asleep, Lorenzo answers in a hollow, disembodied voice, as if a stranger had taken possession of his body.
When he awakens, Lorenzo is overcome with terror. He recalls the images of the plane trip: the turbulence, the plunge into the void, the passengers falling asleep and a strange blue light. Laure and Xavier consult the archives of that period and track down the stewardess. She too has a scar on her forearm, but her implant was surgically removed. Laure returns to the army center and manages to sneak in a USB key on which she records the list of passengers- all but one, who remains unidentified. Erika panics when she hears what Laure has found out: all the children of the passengers on Flight 173 have disappeared. Which means that Lucas, Lorenzo's son, is in danger of being abducted.
Laure dreams of her mother who asks her to stop looking for her. Laure wakes up, troubled. She goes out to her car - a shadow looms. Laure has just been abducted by... Xavier. Suspecting Xavier, the general has him arrested and frees Laure. Laure returns to the Roger's home and brings back a family photo. At the army base, Xavier is injected with truth serum and roughly questioned. Violent memories return. He utters a name... Alex. Laure comes into the interrogation room and explains: "Xavier is Alexandre Roger, the son of Dr. Roger." Xavier confesses to having seen his mother's murder by soldiers who tried to force his father to stop his research on extraterrestrials. He was only 6.
After hearing the confessions of Xavier, Laure asks her father for explanations. He denies any involvement in this affair. At the military hospital, FranĂ§ois and her father find Christopher with his wrists slit, the walls of his room covered with the image of a Crop Circle, drawn in his blood. Laure is horrified. With the help of her uncle Paul Costa, she makes her way through the underground levels of the base and frees Christopher - her father observes it all on his surveillance camera. Regaining consciousness, Christopher leads Laure to a zone cordoned off by barbed wire where they find the crop circle he had drawn. A young girl, Julie, appears suddenly: Christopher stares at her intensely then flees after uttering his first words: "We have to leave... it's written... they'll be coming for us August 12... I have to go find the others..."
Christopher flees and abducts Lucas. Released from prison, Xavier is attacked by Francois who tries to kill him. At police headquarters, Laure aligns the photos of all the vanished and the Crop Circles. She reads: "We are their children... We must gather... on August 12, 2007...To leave... " Noticing the airline stewardess Jeanne Laborde wearing a locket like the one her mother used to have, Laure learns that she got it from her mother on Flight 173. Is she one of them, then? Laure finds Julie, the young woman from the Crop Circle, Christopher, Lucas and Xavier. Xavier warns her that the army is looking for them. Laure takes them to an abandoned monastery. In this grandiose and mysterious place, she collapses into Xavier's arms, revealing that she belongs to another species. The general is relieved of the STAR affair and FranĂ§ois appointed in his place. He is determined to confront Laure.
Laure recovers her personality. She sees herself as a 10-year-old again, running through the fields, her mother telling her that she has to go away. Beams of light had then drawn the Crop Circle. Later, her father had used hypnosis to erase her memories. At the same time, Lucas explains: their parents had been sent deep into outer space in spirit form in order to couple with Earthlings to find the secrets of the life they had lost. They must now return to their own planet. The army recaptures the group but Xavier. In the army cells, they find all the other children of passengers of Flight 173 abducted over the years by the army. Professor Roger had worked in collusion with them. In the underground prison, Manon uses her telepathic powers to make contact with Laure. She tells her that Lucas will be joining them soon to escort them to the departure point.
Laure learns from Professor Roger that her mother was implanted. Meanwhile, MichĂ¨le Costa confesses her secret to Xavier: she knows where Laure's mother is. She takes him to Marseille to the offices of the Planet association. Laure's mother is the one who created this network in order to fight the army and to investigate these extraterrestrial phenomena. Playing his trump card, Xavier takes Irene to the general who realizes that it's his wife Irene who tried to kill his daughter. He provides Xavier with the means to help the prisoners in the base's secret prison escape.
Will Laure find her mother? Will she and her "brothers" escape the army dragnet and succeed in fulfilling the mission for which they were born? To leave...