This movie may have been released in 1945 after the Liberation, but it clearly was shot in 1940, during the "False War", since it it an ensemble comedy set around people in Paris' air raid shelters.
Micheline Presle and Georges Marchal are desperately in love, but his father, Saturnin Fabre, has written a history of Napoleon in which he claims that her mother, Gabrielle Dorziat is not a descendant of that man. Lawsuits fly, and Fabre offers Josephine Baker a discount on her rent if she will have one of her chorus girls distract his son. However, she is all for young love, so for the moment, she's happy to play Friar Lawrence with some musical interludes. Other comics of the era add in marital discord, war profiteering and how tramps adjust to there being jobs for everyone.
It's an amusing French comedy of the cynical variety, but by the post-war era, no one was very interested in it, except possibly for seeing Miss Baker. It got an American release in 1952 in the period when all the sophisticates wanted to see foreign films, then fell back into relative obscurity; four musical numbers and a view of the war that ran contrary to the mythic image chafed. Still, for the trifle that it is, it's a very pleasant one.