Underground chronicles the intertwined lives of two friends during significant historical events: World War II, the Cold War, and the Yugoslav Wars. The narrative begins on the morning of April 6, 1941, in Belgrade, the heart of the Kingdom of Yugoslavia. We meet two charming rogues, Petar Popara, affectionately known as Crni (or Blacky), and Marko Dren, who are returning home after a wild night. As they cruise through the city on a horse-drawn carriage, accompanied by a lively brass band, they boastfully sing and wreak havoc.
Their escapade brings them to the Kalemegdan fortress, where they cheerfully greet Marko's brother, Ivan, who is seen tending to the animals at the zoo. Ivan, a stutterer with a physical disability, greets them with warmth despite his responsibilities. However, the revelry comes to an abrupt halt when Blacky’s pregnant wife, Vera, appears — angry and determined, she chastises him for his reckless behavior, warning him of her intentions to leave, just like Marko's wife left him. Despite this, Marko drunkenly reveals their enrollment of Blacky into the Communist Party (KPJ), which Vera ignores due to her anger over his irresponsibility.
As the story transitions to 1941, the mundane troubles of Blacky’s home life dramatically intersect with the chaos of war. They wake up on a Sunday to the horrifying sound of Nazi aircraft, leading to a bomb drop on their beloved Belgrade. While the city plunges into chaos, Blacky defiantly continues to eat breakfast, and Marko fails to complete an intimate encounter with a prostitute due to the clamor of war. Blacky later ventures outside to survey the destruction, where he encounters the devastated Ivan, who tries to rescue a baby chimp named Soni. In a moment of camaraderie amidst despair, Blacky advises Ivan to maintain his composure — a reflection of their friendship’s depth.
As the level of conflict escalates, Blacky allies himself with Marko and other communists, engaging in clandestine activities including the theft of German weapon shipments. Meanwhile, he visits his mistress, Natalija Zovkov, an acclaimed actress struggling under German occupation, all while caring for her ailing brother, Bata. Blacky navigates their risky relationship, gifting her stolen jewelry while she grapples with the dangers posed by the Germans, particularly as she catches the eye of an influential German officer.
By 1944, the war escalates ever more, leading to a tragic sequence of events involving love and betrayal. Blacky organizes a celebration for his son’s birthday in a dingy communist hideout, amid deep sadness for the loss of his beloved Vera. Tension rises as Marko, now a party secretary, engages in corrupt weapon dealings. In a desperate series of events, driven by twisted loyalty and desperation, Blacky’s rage escalates, culminating in violence at a theater where the stakes of loyalty are tested.
The film transitions from wartime trauma to the struggles of the Cold War era in 1961, where the intrigue surrounding Marko's deception deepens. He keeps Blacky, who is thought dead, hidden in a cellar, manipulating events to sustain a façade. Marko’s ruse is elaborate, involving staged air raids and fake news announcements, ensuring that Blacky remains in the dark about the war's resolution. As Marko enjoys his newfound power and status, Blacky remains a prisoner of the past, preparing secret weapons for a fictional war yet to end.
The final chapter, set against the backdrop of the Yugoslav Wars in 1992, is marked by betrayal, loss, and the ache of nostalgia. Ivan reappears, confronting Marko, leading to their tragic fates intertwined in violence and conflict. In a surreal twist, the film concludes with all those lost, living and deceased, coming together at a wedding, where Ivan delivers a poignant monologue, encapsulating the melancholy and the enduring bonds of friendship and love amid the ruins of history.
