Flight to Berlin (1984)

A mystery involving a woman, Susannah, being taken from her German hotel to be interrogated by police agents, by whom no more than teasing hints are dropped as to what's happened, before the film flashes back to her arrival in Berlin. Susannah meets up with her sister, and then, giving an assumed name, falls in with a handsome young Scot, Jack, at a cafe. He has followed her from her sister's workplace, and it turns out that he, the sister and the sister's husband are all wrapped up in something shady - again it's never clear what.