Didier Mathure, a brilliant space engineer, sees his dreams go up in smoke when his rocket explodes on take-off. He finds himself sidelined at the head of GEPAN, an improbable research group specialising in UFOs.

Didier gets to know his new team and discovers their huge backlog of unresolved cases. He learns that a commission has been set up to investigate the explosion of his rocket, and that his ex-wife, Elise, might testify against him.

The mystery is deepening around the Gondrecourt case. Didier decides to make a deal with the enigmatic Commandant Delbrosse, who claims to have some crucial information.

Didier and Vera are totally flummoxed by the flamingo's sudden disappearance. Didier thought he had reached a scientific dead end until he discovers some space-time anomalies that could be linked to the UFO phenomenon.

Disappointed by Didier, Vera resigns and turns to the Gondrecourt impostor, Duluc, who has become the guru of a sect awaiting the return of the aliens. Didier and Marcel try to recover a video of the mysterious Gondrecourt phenomenon.

Duluc offers Didier a deal: he will give him the video if Didier keeps Delbrosse's team off his back. Didier must come up with a plan.

Didier discovers Commandant Delbrosse's true intentions. Following the success of her intervention at the commission of inquiry, Elise is appointed to replace Didier as head of the Ariane project, but Didier is still hoping to leave with her and put the UFOs behind him. He hands the video over to a young female scientist tasked with studying the phenomenon under a famous Soviet physicist.

Commandant Delbrosse has proof of Didier's collaboration with a KGB agent and bribes him to help her uncover the truth about the phenomenon. Elise is worried when she realises that Didier is increasingly convinced UFOs do exist.

After widespread panic caused by the crash of a satellite that everyone mistook for a flying saucer, Didier is invited to speak on the evening news, but Delbrosse leans on him and asks that he tell the world the truth about the UFO threat.

While Didier and his colleagues are secretly busy trying to decipher the message from the UFOs, a young American filmmaker turns up at GEPAN, keen to make Didier the hero of his next sci-fi movie.

Didier and Vera think they have understood the UFOs' coded message. But while investigating a crop circle in a wheat field, Marcel discovers something that takes them back to square one.

Didier's colleagues are shocked when they find his report recommending the closure of GEPAN, and they send him packing. Meanwhile, Didier realises that a terrible danger threatens a gathering attended by his daughter in Larzac. He sets out to save her.