The conflicts and the joys of each member of the Kervelec family reveal the complexities of inter generational relationships, from grandparents to grandchildren.

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.

The disappearance of a young woman puts two forensic police officers on the trail of a serial killer. Their fears are confirmed by the discovery of several corpses, what follows is a long hunt across Paris.