In November 1942, at the Wolf’s Lair in East Prussia, Leader of Nazi Germany Adolf Hitler selects Traudl Junge as his personal secretary. Three years later, the Red Army has pushed Germany’s forces back and surrounded Berlin. On Hitler’s 56th birthday, the Red Army begins shelling Berlin’s city centre. Reichsführer-SS Heinrich Himmler tries to persuade Hitler to leave Berlin, but Hitler refuses. Himmler leaves to negotiate terms with the Western Allies in secret. Later, Himmler’s adjutant Hermann Fegelein also attempts to persuade Hitler to flee, but Hitler insists that he will win or die in Berlin. Dr. Ernst-Günther Schenck is ordered to leave Berlin per Operation Clausewitz, though he persuades an SS general to let him stay in Berlin to treat the injured. In the streets, Hitler Youth child soldier Peter Kranz’s father approaches Peter’s unit and tries persuading him to leave. Peter, who destroyed two enemy tanks and will soon be awarded a medal by Hitler, calls his father a coward and runs away.

At a meeting in the Führerbunker, Hitler forbids the outnumbered 9th Army to retreat, instead ordering SS commander Felix Steiner’s units to mount a counter-attack. The generals find the orders impossible and irrational. Above ground, Hitler awards Peter his medal, hailing Peter as braver than his generals. In his office, Hitler talks to Minister of Armaments Albert Speer about his scorched earth policy. Speer is concerned about the destruction of Germany’s infrastructure, but Hitler believes the German people left behind are weak and thus deserve death. Meanwhile, Hitler’s companion Eva Braun holds a party in the Reich Chancellery. Fegelein tries persuading Eva, his sister-in-law, to leave Berlin with Hitler, but she dismisses him. Artillery fire eventually breaks up the party. On the battlefield, General Helmuth Weidling is informed he will be executed for allegedly ordering a retreat. Weidling comes to the Führerbunker to clear himself of his charges. His action impresses Hitler, who promotes him to oversee all of Berlin’s defences. At another meeting, Hitler learns Steiner did not attack because his unit was too weak. Hitler becomes enraged at what he sees as an act of betrayal and launches into a furious tirade, stating that everyone has failed him and denouncing his generals as cowards and traitors, before finally acknowledging that the war is lost, but that he would rather commit suicide than leave Berlin.

Schenck witnesses civilians being executed by German military police as supposed traitors. Hitler receives a message from Luftwaffe chief Hermann Göring, requesting state leadership. Hitler declares Göring a traitor, ordering Göring’s dismissal from all posts, arrest, and execution in the event of his death. Speer makes a final visit to the Führerbunker, and admits to Hitler that he has defied his orders to destroy Germany’s infrastructure. Hitler, however, does not punish Speer, who decides to leave Berlin. Peter’s unit is defeated and he runs back to his parents. Hitler imagines more ways for Germany to turn the tide. At dinner, Hitler learns of Himmler’s secret negotiations and orders his execution and also finds out that Fegelein has deserted his post, having him executed despite Eva’s pleas. SS physician Ernst-Robert Grawitz asks Hitler’s permission to evacuate for fear of Allied reprisal. Hitler refuses, leading Grawitz to kill himself and his family. The Soviets continue their advance, Berlin’s supplies run low, and German morale plummets. Hitler hopes that the 12th Army, led by Walther Wenck, will save Berlin. After midnight, Hitler dictates his last will and testament to Junge, before marrying Eva. The following morning, Hitler learns that the 12th Army is stuck and cannot relieve Berlin. Refusing surrender, Hitler plans his death. He administers poison to his dog Blondi, bids farewell to the bunker staff, and commits suicide with Eva. The two are cremated in the Chancellery garden.

Propaganda Minister Joseph Goebbels assumes the Chancellorship. General Hans Krebs fails to negotiate a conditional surrender with Soviet General Vasily Chuikov. Goebbels declares that Germany will not surrender as long as he is alive. Goebbels’ wife Magda poisons her six children with cyanide, before committing suicide with Goebbels; Weidling announces unconditional surrender of German forces in Berlin afterwards. Many government and military officials commit suicide after learning of Germany’s defeat, including Krebs. Peter discovers his parents were executed. Junge leaves the bunker and tries to flee the city; Peter joins her as she sneaks through a group of Soviet soldiers before the two find a bicycle and leave Berlin.