In Spring 1917, three years into the First World War, 17-year-old Paul Bäumer enlists in the Imperial German Army alongside his school friends, Albert Kropp, Franz Müller, and Ludwig Behm. They listen to a patriotic speech by a school official and unknowingly receive uniforms from soldiers killed in a previous battle. After they are deployed in Northern France near La Malmaison, they are befriended by Stanislaus "Kat" Katczinsky, an older soldier. Their romantic view of the war is shattered by the realities of trench warfare on the Western Front, and Ludwig is killed by artillery on the first night.

On November 7, 1918, German official Matthias Erzberger, weary of mounting losses, meets with German High Command to persuade them to begin armistice talks with the Allied powers. Meanwhile, Paul and Kat steal a goose from a farm to share with Albert, Franz, and another veteran, Tjaden Stackfleet, with whom they have grown close behind the front in Champagne. Kat, who is illiterate, gets Paul to read him a letter from his wife and worries that he cannot reintegrate into peacetime society. Franz spends the night with a French woman and brings back her scarf as a souvenir.

On the morning of November 9, General Friedrichs drives Erzberger and the German delegation to a train bound for the Forest of Compiègne to negotiate a ceasefire. Paul and his friends go on a mission to find 60 missing recruits sent to reinforce their unit and discover that they were killed by gas after taking off their masks too soon. Friedrichs, who opposes the talks, orders an attack before French reinforcements arrive. That night, Erzberger's delegation reaches the Forest of Compiègne, and Paul's regiment is sent to the front to prepare to attack the French lines.

On the morning of November 10, Ferdinand Foch, the Supreme Allied Commander, gives 72 hours for the Germans to accept the Allied terms, with no room for negotiation. Meanwhile, the German attack takes the French front line after hand-to-hand fighting but is routed by a combined arms counterattack with Saint-Chamond tanks, airplanes, and flamethrowers. Franz is separated from the group, and Albert is killed trying to surrender. Trapped in a crater in no man's land with a French soldier, Paul stabs him and watches him die slowly, becoming remorseful and asking forgiveness to his dead body. Erzberger learns of Kaiser Wilhelm II's abdication and receives instructions in the evening from field marshal Paul von Hindenburg to accept the Allied terms. Paul returns to his unit and sees them celebrating the imminent end of the war. He finds a wounded Tjaden, who gives him Franz's scarf. Paul and Kat bring him food but Tjaden, distraught at being crippled, kills himself.

Around 5:00 AM on November 11, Erzberger's delegation signs the armistice set to take effect at 11 AM. After learning of the ceasefire, Paul and Kat steal from the farm one last time, but Kat is shot by the farmer's young son and dies as Paul carries hi