Working late one night, Sylvie (Bonnaire) discovers her brother Paul (Colin) searching her desk for a handgun. He says he's found out that their father's death five years past was murder - he has evidence implicating Walser (Radziwilowicz), their father's closest colleague. Sceptical and instinctively cautious, Sylvie is compelled to follow up the investigation to save her brother from himself, or so she thinks. Rivette doesn't exactly cut to the chase. The most memorable sequence follows Sylvie as she goes into the Métro. She boards the train, deep in thought, and Rivette stays with her in real time right through to the next stop, where she alights, crosses to the next platform, and waits again. A decision has been reached. The scene is by no means atypical. Rivette seems intent on probing that which must remain unspoken, on photographing the unconscious - hence the title, which translates as 'Top Secret'. Sternly ascetic and unerringly contemplative, this 170-minute film is, nevertheless, a thriller - and something of a potboiler at that. It's a problem, because for all its mysteries, the movie thoroughly repudiates suspense. What the film does have in its favour is a performance of concerted, gaunt integrity from Bonnaire.