In 1942, a group of German secretaries are escorted to Adolf Hitler's (Bruno Ganz) compound at the Wolf's Lair in East Prussia. After dictating to her for a moment and despite multiple mistakes, Hitler selects Traudl Humps (Alexandra Maria Lara) to be one of his personal secretaries.
The scene shifts to Hitler's 56th birthday on April 20, 1945. Secretary Traudl Humps (now Traudl Junge) is awakened in the Führerbunker by the sound of Soviet artillery. Later, Generals Wilhelm Burgdorf and Karl Koller confirm to a surprised Hitler that the Red Army is just 12 kilometres from the city centre. Later, at his birthday reception, Reichsführer-SS Heinrich Himmler (Ulrich Noethen) and his SS adjutant Hermann Fegelein (Thomas Kretschmann) plead with Hitler to allow himself to be evacuated from the city. Instead, Hitler declares, "I will defeat them in Berlin, or face my downfall." Himmler leaves Berlin with the intention of negotiating surrender terms with the Western Allies behind Hitler's back.
In another part of the city, a group of Hitler Youth members continue to build up defenses for the defense of Berlin. Peter, a boy in the group, is vainly urged by his father to desert and flee the city. Later, Peter's unit is part of a group which is awarded the Iron Cross by Hitler.
Meanwhile, SS Dr. Ernst-Gunther Schenck (Christian Berkel) is ordered by the high command to evacuate Berlin, as part of "Operation Clausewitz". Schenck pleads with an SS general to be permitted to remain in order to look after the wounded and starving. The general grudgingly agrees to permit this. Schenck is requested by Brigadeführer Wilhelm Mohnke (André Hennicke) to bring all the medical supplies he can obtain to the Reich Chancellery. While doing this, Schenck and his adjutant go to a hospital in search of medical supplies. They approach a tank position where a panzer commander informs them that everyone has left the hospital, and to be careful of the Russian troops in the area. Inside the hospital, Schenck finds the basement filled with elderly and infirm patients. After retrieving what medical supplies are available, Schenck and his adjutant try without success to prevent the summary execution of two old men by Feldgendarmerie (military police).
In the bunker, Hitler discusses his new scorched earth policy with his favourite architect and trusted friend, Albert Speer. The latter pleads for mercy for the German people, saying that Hitler's plans will return them to the Middle Ages. Unmoved, Hitler retorts that the German people have shown themselves weak and therefore do not deserve to survive. Speer confesses to Hitler that he has sometimes disobeyed orders but is nonetheless allowed to leave the city. Eva Braun (Juliane Köhler) ignores Fegelein's pleas to leave Berlin and holds a party for the bunker inhabitants up in the Reich Chancellery, but Soviet artillery shells end the party early.
The next day, General Helmuth Weidling is mistakenly thought to have ordered a retreat to the West and ordered to the bunker. Believing he is about to be executed Weidling explains himself to Burgdorf and Hans Krebs, only to find himself appointed commander of the Berlin Defense Area, much to his dismay. In the briefing room at the bunker, Hitler is informed about the disintegrating defenses of Berlin. Unmoved, he announces that Waffen SS General Felix Steiner will soon arrive and drive the Red Army out of the city. However, he is then informed that Steiner couldn't mobilize enough men. Visibly shaken, Hitler dismisses all except Joseph Goebbels, Martin Bormann and Generals Wilhelm Keitel, Alfred Jodl, Krebs, and Burgdorf.
Throwing a massive tantrum, that is heard clearly by those outside the room, Hitler furiously accuses the Wehrmacht and even the SS of sabotaging him from day one. He screams that the soldiers are all cowards and traitors, despite a rebuke of that position by Burgdorf, and that the generals are "the scum of the German people." He expresses regret at not executing the entire officer corps, like Joseph Stalin did during the Great Purge. At last, however, Hitler sinks into his chair and acknowledges that the war is lost. "If you think that this means I'll be abandoning Berlin", he snarls, "I'd rather shoot a bullet through my head."
Brigadeführer Mohnke is shown fighting on the front lines with his troops when he observes a group of civilian volunteers running to their deaths in the streets. Mohnke asks one of his adjutants for a situation report. The officer informs him that the civilians are members of the Volkssturm, and they are under Goebbels' direct command. Disgusted, Mohnke orders the officer to get the Volkssturm out of the line of fire, and states he will take responsibility for doing so.
Mohnke makes his way back to the Reich Chancellery to confront Goebbels about the Volkssturm. Goebbels is in the bunker communications room talking to his wife Magda. Goebbels tells her to bring the children to the bunker and not to bring many toys or nightclothes, which are no longer necessary. Thereafter, Mohnke tells Goebbels that the Volkssturm are nothing but cannon fodder for the Russians. In response, Goebbels bristles and informs Mohnke that their belief in "final victory" makes up for their lack of weapons and combat experience. Mohnke tells Goebbels that if these men do not have weapons their deaths are pointless. Goebbels informs Mohnke that he has no pity for them, adding, "The German people chose their fate and now their little throats are being cut."
Later Hitler, Eva, Traudl Junge, and Gerda discuss various means of suicide whilst (in another area of the bunker) Krebs, Burgdorf and other military staff sit around getting drunk. Hitler proposes shooting through the mouth, while Braun mentions taking cyanide. Hitler gives Gerda and Traudl one cyanide capsule each. Eva Braun and Magda Goebbels type goodbye letters: Eva to her sister Gretl Braun and Goebbels to her adult son (from her former marriage) Harald Quandt. The child soldiers fight in the streets of Berlin, but to no avail. Peter witnesses the death of all his squad mates and flees home to his parents.
Meanwhile, Hitler has lost his sense of reality. Field Marshal Keitel is ordered to find Admiral Karl Dönitz, who Hitler believes is gathering troops in the north, and help him plan an offensive to recover the Romanian oilfields. Oberscharführer Rochus Misch, Hitler's radio operator, receives a telegram from Hermann Göring, head of the Luftwaffe and Hitler's designated successor. Bormann reads the telegram to Hitler, in which Göring asks permission to assume command of the Reich and asks for acknowledgment by 10:00 pm, at which time he will assume authority in the absence of a response. Walther Hewel tries to justify his actions but Bormann and Goebbels declare Göring's actions to be high treason; Hitler orders Göring's arrest and removal from office.
Hitler summons General Robert Ritter von Greim (Dietrich Hollinderbäumer) and his mistress, ace pilot Hanna Reitsch, to the bunker. He appoints von Greim to be Commander-in-Chief of the Luftwaffe, ordering him to rebuild it. During dinner, Hitler receives a report informing him that Himmler has just attempted to negotiate a separate peace settlement with the Western Allies. Betrayed by the one man he trusted, Hitler explodes in another tearful outburst. He then orders von Greim and Reitsch to leave Berlin, rendezvous with Dönitz, who he is convinced is rallying troops and preparing a massive pincer strike alongside Field Marshal Albert Kesselring, and ensure that Himmler is dealt with.
Reichsphysician SS Ernst-Robert Grawitz, whose earlier request to leave Berlin had been denied, returns to his apartment and kills himself and his family with grenades.
Hitler wishes to speak to Fegelein with regards to Himmler's treachery but Fegelein has deserted the bunker and plans to flee the country. He is tracked down to his apartment by SS troops and arrested. Despite a tearful plea from Eva Braun to spare her brother-in-law's life, Hitler is unmoved and denounces him as a traitor. Fegelein is promptly executed by a firing squad.
General Weidling reports that the Russians have broken through everywhere. There are no reserves and air support has ceased. Mohnke reports that the Red Army is only 300 to 400 meters from the Reich Chancellery and that defending forces can hold out for a day or two at most. Before leaving, Hitler reassures the officers that General Walther Wenck will save them all. After he leaves the conference room, Weidling asks the other generals if it is truly possible for Wenck to attack; they all agree it is unlikely, even impossible, that Wenck will succeed, but do not wish to surrender.
The following day, Hitler dictates his personal statement to Traudl Junge before marrying Eva Braun. Hitler has ordered Joseph Goebbels to leave Berlin, but Goebbels intends to ignore the order. When Hitler's adjutant Otto Günsche later brings a reply from Keitel that Wenck's army is encircled or cannot continue its assault on Berlin, Hitler states that he will never surrender. He also forbids all officers to surrender on pain of summary execution. Upon leaving the conference room Hitler gives Günsche the order to cremate his body and that of Eva Braun.
Schenck, Dr. Werner Haase, (Matthias Habich) and a nurse are summoned to the bunker and Haase tells Hitler the best method for suicide as well as administiring poison to Blondi which Schenck witnesses. Waffen SS soldiers carrying the gasoline to burn Hitler's and Braun's corpse arrive soon after.
Eva affectionately gives Traudl one of her best coats and makes her promise to flee the Bunker. Hitler eats his final meal in silence with Constanze Manziarly and his secretaries. He bids farewell to the bunker staff, gives Magda his Golden Party Badge (marking original members of the NSDAP from February 27, 1925 to November 9, 1933, with numbers 1 to 100,000), and retires to his room with Eva. Although Magda pleads with him to change his mind, Hitler states, "Tomorrow, millions of people will curse me, but fate has taken its course."
Hitler and Eva retreat into their rooms and commit suicide. The bodies of Hitler and Eva Braun are carried up the stairs to ground level and through the bunker's emergency exit, doused in petrol and set alight in the Reich Chancellery garden outside the bunker. From the bunker entrance, surrounding officers give one final Nazi salute over the flames. General Krebs leads a small delegation through the Russian lines and tries to negotiate peace terms with General Vasily Chuikov. Chuikov says that the Soviets will only accept unconditional surrender but Krebs does not have the authority to grant this so he returns to the bunker empty-handed. Unable to comprehend a world without National Socialism, Joseph and Magda Goebbels poison their six children and leave the bunker complex. Goebbels shoots his wife before shooting himself.
The people remaining in the bunker agree that they must try to break out of the Soviet encirclement. Krebs and Burgdorf commit suicide as the rest begin to evacuate. Most of the bunker survivors attempt to escape, but die at the hands of Red Army infantrymen. Weidling then goes out and broadcasts to the soldiers and civilians in Berlin that the Führer is dead. He has called for a ceasefire with Lieutenant-General Vasily Chuikov as every further hour of battle will merely postpone the inevitable.
Meanwhile, Schenck and Hewel stay with Mohnke and his remaining SS troops, who debate on what to do once the Soviet troops arrive. Schenck tries to talk sense into Hewel, who promised Hitler that he would kill himself. When news reaches the officers that Berlin has been surrendered, Hewel and several of the SS officers promptly shoot themselves, as they had promised, to Schenck's dismay.
In the chaos of the city's fall, Traudl Junge is able to make her way through the Russian lines, escaping from Berlin by bicycle along with the child soldier Peter. The subsequent fates of the surviving characters are superimposed and the credits roll.
