Passage To Marseille is consciously a successor to Casablanca, sharing many cast and crew members, most notably Humphrey Bogart (this time cast as a French citizen, which is helpful to be told because he makes no attempt at an accent of any type).
And though wartime uncertainties and evocative exotic cities are held in common, Passage To Marseille shares little with its storied predecessor.
To its credit the characters of the returning cast members are distinctly different.
Such is the impact of the earlier movie, my expectations in that regard were consistently overturned.
While Casablanca was based on a play, Passage was based on a novel.
While Casablanca portrays an intimacy that flows from the stage, and uses flashback judiciously to provide timely context to characterisation; Passage has broad narrative sweep, and an amazingly complex structure of flashbacks that would work in the chapters of a novel but present a challenge in maintaining a consistent development of its story.
Whereas Casablanca takes us to Paris and back; at one point Passage takes us to a flashback that contains a flashback that contains a flashback that contains a flashback.
So, Passage To Marseille is very self-consciously its own movie.
And perhaps in an indication of how the historic events that had occurred between the two movies had impacted public consciousness, Passage seems more at home in the darkness.