After the success of Mister Twister Class of Fun and Mister Twister goes camping, Holland’s favourite student teacher returns with a third adventure. In Mister Twister on stage, Mr Casey’ class is putting on a show. They are super-excited about it, until they find out that Ms Dreus, the headmistress, has picked a boring medieval play for them to do. Then Mr Casey has a totally different idea that still looks a bit like what she wanted… It’s a typical Mr Casey solution. But when the old class teacher returns and Ms Dreus finds out that Mr Casey has turned everything on its head, he is sent to teach nursery and it looks like everything is about to go wrong for Tobias, Sep and the rest of the class.
Mr Casey’ class gets to put on a play. Everyone is super-excited about it, until they find out that Ms Dreus, the headmistress, has picked an extremely boring play for them to do. It also has to be performed in the local old people’s home, which is a bit of a scary place. Mr Casey tries to come up with solutions and manages to put his own spin on the show, in that way that only Mr Casey can. Just when everything seems to be going well, Ms Dreus tells them that their old teacher is coming back from maternity leave. Mr Casey will have to go. The whole class is in uproar. They are outraged that Mr Casey has to leave. Mr Casey himself is quite upset about it as well, but there is nothing he can do about it. After all, he is only a student teacher and the teacher is a real teacher. He has to go to the nursery, where according to the headmistress’ rules, Mr Casey will have to do a six month placement. The children try to be kind to their teacher, but they really miss Mr Casey! Will everything turn out alright in the end?