Teachers Martin (Mads Mikkelsen), Tommy (Thomas Bo Larsen), Peter (Lars Ranthe), and Nikolaj (Magnus Millang) are not just colleagues; they are friends navigating the challenges of teaching at a gymnasium school in Copenhagen. All four are grappling with the disinterest from their students, which has caused their own lives to feel monotonous and unfulfilling. The situation escalates when Martin faces criticism from his senior students and their parents, who blame him for hindering their chances of passing history exams.
During a dinner celebrating Nikolaj's 40th birthday, a provocative discussion unfolds regarding a theory proposed by psychiatrist Finn Skårderud—the idea that humans are inherently born with a blood alcohol content (BAC) deficiency of 0.05%. According to Skårderud, maintaining this level can lead to enhanced creativity and relaxation. Intrigued, the friends decide to put this theory to the test through a unique experiment, documenting their experiences as they drink at intervals to sustain this blood alcohol level. For Martin, dealing with personal issues like his depression and feeling distant from his family makes this experiment particularly appealing, while Nikolaj suffers from a strained relationship with his wife, who appears to harbor disdain for him.
The group establishes strict rules to guide their experiment: they must keep their BAC at a minimum of 0.05 during workdays and refrain from drinking after 8:00 PM or on weekends. Although all men find clever ways to sneak drinks throughout the day—even while teaching—safety remains a priority, as they never drive under the influence, understanding that 0.05 is the legal limit.
Not long into their experiment, the friends begin to enjoy notable improvements in both their professional and personal lives. Martin, especially, finds joy as he reconciles with his wife and children. His history lessons gain a fresh perspective, and he captures his students' attention, making class not just enjoyable but also significantly relevant through the context of alcohol. Encouraged by their initial successes, the friends decide to raise their BAC limit to 0.10. However, one fateful night, they indulge too heavily, testing the limits of their newfound liberation. The aftermath results in a confrontational wake-up call from their families, revealing the extent of their drinking. Martin learns that his wife has known about his drinking habits and has been unfaithful, prompting the group to abandon their experiment in disarray and personal turmoil.
As time goes by, the friends agree to stop drinking during the day—except for Tommy, whose struggle continues. At a faculty meeting, where the headmaster addresses the issue of teachers drinking at work, Tommy makes a drunken appearance that raises alarms. Tragically, after an ill-fated decision to set sail with his old dog, Tommy drowns at sea.
After Tommy's funeral, Martin, Nikolaj, and Peter gather for a dinner to honor him. Sipping on sparkling wine, a connection begins to rekindle as Martin texts his wife expressing his longing for her. She replies with a similar sentiment. Suddenly, a group of recently graduated students, amidst their boisterous celebrations, passes by, sparking a sense of nostalgia and spontaneous fun. The trio joins them by the harbor, where Martin finds himself dancing with abandon—a joyful moment he had previously shunned. His dance, once hesitant, evolves into a spirited performance, culminating in an exhilarating jump off the harbor wall into the bay, embodying a fleeting yet profound sense of liberation.
