Mick Travis (Malcolm McDowell) is a junior at a british boarding school. The seniors act sadistically towards Mick and his two pals because they are considered independent and rebellious.
This film takes a good hard look at British Boarding schools and presents the idea that it is more about preserving traditions and the class system than education.
Mick and his pals discover a cache of weapons and launch an assault against the faculty and the visiting alumni on founder's day.
The film ends with Mick shooting a machine gun and then fading out to the title "if....".
Thanks Don P!