Based on Bjarne Reuter's 1975 juvenile novel, even broader comedy strokes are employed in the film version, but bright spark Bertram is still at the center of things when a nice but dubious uncle (he has a criminal record) takes all the kids of a working class family, hit with bad luck, away on an outing. A plot is cooked up to kidnap some rich kid. It works at first, but soon things get out of control.