This is the third and final part of the now famously successful trilogy, where Mr. Müller and his problem kids Chantal, Danger and Co. once again take up arms against their sworn enemy, the German education system.
Isi doesn't get the world anymore. Just a short while ago, life was wild, fun, and without obligations, but suddenly everyone around her seems to be grown-up and successful. With her diploma in one hand and a drink in the other, she is stuck between the careless days of college and real life. When her best friend Lotte gets a respectable job and becomes pregnant, Isi realizes that she needs to find a way to start living a life on her own.
Mr. Müller is not satisfied with his new work at the Goethe-Gesamtschule. The early getting up and correcting exams annoy him. Director Gerster wants to improve the image of the Goethe-Gesamtschule because she wants to be a symbol of the new company. To achieve this, she wants to take away the partnership from the Schillergymnasium with a Thai school. So, Mr. Müller, Mrs. Schnabelstedt and the 10b must go on a school trip to Thailand.
교도소에서 막 출소한 제키(엘리아스 므바렉)는 훔친 돈다발을 묻어두었던 장소를 찾아가지만 이미 학교 건물이 들어서 있다. 포기할 수 없던 그는 어리버리해 보이는 여선생(카롤리네 헤어퍼스)을 속이고 학교에 임시교사로 취직하여 낮에는 교사로, 밤에는 땅굴을 파며 생활한다. 소위 꼴통 학교의 분위기는 점차 조금씩 변하게 되고 누구의 말도 듣지 않던 문제아들은 제키의 말을 듣고, 절대적으로 그를 따르게 된다. 뭔가 다른 이 선생님, 그의 매력에 모두 빠져들게 되는데..
