During WWII, the Swedish military comes to Nils-Erik Kristersson's farm and inform him that they will be staying there for a month. Because he has several black market dealings in the works with a local wholesale dealer and the soldiers will notice, he plans to get them out of the area by staging an outbreak of the mumps. Meanwhile, the wholesale dealer visits and takes an interest in Nils-Erik's daughter and also, strangely, in the military's objectives in the area. Also, the farm's maid takes a fancy to one of the soldiers, making her boyfriend jealous.