Ivo is a Serbian POW & Lisa is the wife of the Bulgarian Colonel who is practically the head of the cantonment town. The Colonel is well-respected by his unit. He is also quite a committed and ruthless army man who is not above starving the POWs if only to avoid a mutiny. Although he seems to have positive aspects too but he is capable of being quite cold, even with his own wife. He knows that his country is on the verge of losing the war but he refuses to believe that all the suffering & casualties could soon amount to nothing. His wife Lisa, on the other hand, is a kind-hearted & intellectual woman who is sick of seeing the war & the suffering & wants it all to be over. She is feeling trapped & suffocated in her marriage with a man who rarely ever shares his true feelings with her. Moreover, so fixated is the Colonel on the war and his country that he fails to see his own wife's desperation and despair.
Ivo enters Lisa's life at this very crucial point. He is a Serbian officer who used to be a teacher before he was enlisted in the war. Ivo & Lisa realize that even though they have different nationalities, they both want a peaceful existence. I must concede that the romantic angle could have been justified a bit better but I can see how these two people would gravitate towards each other. If all you see around yourself is death & destruction, then you are bound to rush towards a like-minded individual who offers you love and a few moments of peace.
The only thing that could've made the movie a bit more interesting would have been the Colonel getting to know about the affair & his reaction to it. Would he have realized that between love and war, it's the former that is more important? Or would he simply have branded his wife an adulteress & given her up? Or would he have ignored the affair & carried on with their lives as before? Lots of potential there.
