Fort Alpha is the nickname for a school called " Het Alpha College".
The series centralized on one of the classes in the school, 4 HAVO B (or 4B in short). The students in the class, all have their own little problems, this spans from using drugs to animal protection, recording a record from someone else to leaving school due to career moves and multi-cutural issues, etc.
4B is described as the most difficult class in the school and if there's trouble, it's always 4B that's involved.
Not only do the students have problems, the teachers also seem to have some issues and not only with the students, but with other teachers and at home.
The two janitors seem to be the only two persons to whom is listened by the students.