This film tells the story of Ronald, an intelligent boy who wants to become an architect or surveyor. His cousins Paul and Jane cannot believe that Ronald has any awareness of building sites. In Paul's imagination, he and his sister set Ronald in a number of typical sites, to see if he can survive the hazards that kill and maim many children each year. Ronald eventually learns the hard way that he did not know as much about building sites as he thought.

The girls of St Trinian's decide they are being asked to do too much work so they go on strike.