Alan Ladd stars with Geraldine Page in the riveting war time spy thriller. The story opens at an Army spy school where tactics and gadgets used in espionage operations are demonstrated to students -- as well as the sobering lesson that one wrong move could cost them their lives. A cunning captain (Ladd) of an O.S.S. team is sent undercover into Nazi-occupied France to blow up a railway tunnel. With danger constantly at their backs, the team carefully plots a course of action while the enemy is closing in and D-Day is fast approaching.