I am trying to track down a movie from the post-war era that I saw on TV many years ago. It is English-language, but could be either American or British.

I mainly remember it for being an atmospheric suspense thriller with a very distinct vibe from the chaotic time right after WWII had ended. The setting is a partially bombed-out city in Europe. My recollection of the plot is hazy, but the main characters are a couple, possibly married, who had worked together during the war. I think they had been involved in the resistance movement together.

At the outset of the movie they look forward to returning to a normal existence, but somehow the man is jailed for a crime he didn’t commit, and the woman is left to track down the real criminal on her own in order to prove his innocence. There is some additional suspense — it seems to me that maybe she is trying to evade capture as well, I’m not sure.

The female character is very capable and is really driving the action through much of the movie. What I particularly remember is that they use their wartime skills to communicate while he is in prison, without his jailers ever realizing that the two are in contact.

The climax of the movie takes place in some huge ruin, maybe a bombed-out cathedral.

I have no idea who the actors were. They were not big Hollywood names, and the movie seemed to be shot in the actual ruins of some European city, which leads me to think that it is most likely a British movie.

I have been trying to track this down for years, and I would be so-o-o-o grateful if anyone can help me figure it out.