The Interpreter
Nicole Kidman stars as UN translator Silvia Broome in this political thriller from Sydney Pollack (who also has a smallish role in the film).
Early on, we find out that Silvia has overheard someone speaking an obscure African dialect about murdering a visiting dignitary. Even stranger, that dialect is spoken in her country of origin, a fact pointed out by Sean Penn, playing haunted secret service agent Tobin Keller.