 After a few burglaries, the city borough s most arrogant busybody Mrs. Hulpiau, whose mailbox was vandalized, gets landlady Jeanne to "volunteer" everybody for a neighborhood watch (hence the Dutch title). They all think it s absurd, but once found out to have committed minor nightly vandalism as a prank they don t dare refuse since Jeff and Odilon, being in the civil service, could loose their jobs. So patrol duos are formed, only too eager to concentrate on anything but crime: playing with the walkie-talkies, hiding to duck patrol duty. The only exception are Jeanne and Ria, the students  own busybody, but when man-eater Betty throws her older lovers cloths out of the window for spending too little time on her, the reported  naked man on the roof  sends them panicking and calling the police, which by now is no longer amused after several false alerts.