Both are deported by the Soviets to Siberia, where they briefly meet again when signing up to the newly created Polish army.
Again separated from Irena, Adam marches with the army from Siberia through the Middle East and fights on the Italian front line.
In the military hospital, a nurse finds his diary and, initially with the intent to relieve his suffering, later forms romantic affection towards him and pretends to be his fiancée Irena.
Adam recovers from his wounds and, after the Polish victory at Monte Cassino, follows the army together with Irena to northern Italy, where they settle after the end of the war.
The name of the film, Wielka Droga, means 'The Great Way', referring to the march from Poland through Siberia and the Middle East to Northern Italy.