Four friends who all teach at the same high school (history, psychology, music and gym) are subsiding into boring middle age. Martin (Mads Mikkelsen) the history teacher is summoned to a meeting with his class and parents where concerns are expressed about his teaching style and that they will not get the exam grades they need for Uni.

At a 40th birthday meal out for the four they drink freely and subsequently discuss a psychologists theory that humans should naturally have a constant blood alcohol level of 0.05% (the UK driving limit is 0.08%). They agree to conduct an experiment to maintain a constant 0.05% level during the working day and record their experiences. The results are promising - they all see improvements in their teaching and find their social relationships improved.

Inevitably they step it up a level to see what happens if they simply drink enough to maintain a level that they feel comfortable with, and then to see what happens if they drink as much as possible.