40-year-old Bertrand has been suffering from depression for the last two years and is barely able to keep his head above water. Despite the medication he gulps down all day, every day, and his wife's encouragement, he is unable to find any meaning in his life. Curiously, he will end up finding this sense of purpose at the swimming pool, by joining an all-male synchronised swimming team.

In 35,000 BC, the tribe of the Dirty Hairs is at war against the tribe of the Clean Hairs for eight hundred years, trying to get their shampoo. The chief of the Dirty Hairs sends his daughter Guy disguised to the enemy tribe to get some shampoo for his tribe. When the healer of the Clean Hairs tribe surprisingly kills two cavemen of his tribe, their imbecile chief assigns Pierre with curled hair and Pierre blonde to investigate the murder and find the criminal.