La maison des filles perdues (1974) - Pierre Chevalier

In a luxurious villa in a remote part of the country, girls are taken against their will to work as prostitutes. One of the girls, with the help of one of her customers, manages to escape. She goes to the police for help. A detective investigates the case and finds more than he bargained for.

Convoi de filles aka Convoy of Girls (1978) - Pierre Chevalier & Jesus Franco

Young German officer Erich von Strasser (Jean-Marie Lemaire) leaves his fiance and heads off to war. Stock footage of Nazi desert warfare plays and before you know it Erich is back in Germany, recipient of the Iron Cross and a national war hero. First stop the whorehouse then, naturally. Where he bumps into his fiance, awkward. Cue a flashback showing how/why she ended up there and after a night of passion Erich goes to his superiors asking she be freed. Unfortunately, for reasons still unclear to me, she is shipped off to another location and Erich sets off in pursuit.