Lieutenant Ville Somero investigates a sabotage at a fortress site on the Karelian Isthmus in the summer of 1939. His suspicions are directed at the guests of a nearby guesthouse. Aarno Teräs an engineer leading the fortification site, and his bride Birgit Lahti get into trouble because of a band of spies and dancer Veronica Sorrento.
A man mixed up in suspicious activity is murdered in the studio of photographer Ilmari Lavio. At the same time a charming woman has entered the studio, but Lavio does not want to report her to the police. The photographer begins to follow the beauty who calls herself Soile Mäntymaa and through her traces a league of spies.
At the eve of Crimean war orphaned Regina lives with her grandmother in a small cabin near a lavish villa. As the summer approaches there is great anticipation of a big ball to be held.
The priest's daughter, Vappu Kankare first irritates and then admires the ambitious habitant, Jalmar "Jali" Kinnunen. After the studies, Vappu and Jali get married, but the marriage is disappointing.
