The Pinchers are anything but an ordinary family: mother Fia, father Bove, sister Criminelle, and even their dog Cop are hardened criminals. They plan to steal the world's most valuable object from a museum: Farah Diba's coronation diadem. Everything goes according to plan until Ture, the family's son, shows up. Honest Ture has never stolen anything and tries to prevent the others from stealing the tiara. The robbery fails due to the museum's super-efficient security system, and the trio is forced to get on the straight and narrow, much to Ture's delight.

Mother, father, and daughter eagerly participate in a support group for ex-master thieves, and everything seems to be going well. At the same time, the easygoing police officer Paul Eastman gets a new case, which Ture helps him solve. The boy immediately sets out to solve the mysterious dognapping. Is it a coincidence that the missing dog looks like the Pincher family pet? And has the family really left their thieving ways behind? What do the creepy twins really want?