The Man Who Knew Too Much (1956)

Dr. Ben McKenna (James Stewart) is on vacation with his wife (Doris Day) and son in Morocco when a chance encounter with a stranger sets their trip, and their lives, on a drastically different course. The stranger, killed in front of the family in the marketplace, reveals an assassination plot to the Americans. The couple's son is abducted in order to ensure the plot is kept secret, and suddenly the mother and father, with no help from the police, must figure out a way to get their child back.