The film follows Finnish army machine gun company in Continuation War against Soviet Union, 1941–1944. Based on Väinö Linna's best selling novel Tuntematon Sotilas (The Unknown Soldier) and the novel's uncensored version, Sotaromaani (A War Novel).

The summer ahead is long and hot but the burden of shame from the past is haunting Joonas, 24, and driving him to solitude. A sudden phone call changes the direction of his summer and brings Joonas to an old manor for a summer job, forcing him to open up to his new workmates and to face his shame. Joonas works hard under the burning sun, driven by his past mistakes, whilst the others lounge under the calming shade of trees. On the last day the group loses track of time and misses the last bus home. They are left at the old manor and a magical midsummer night begins.