Les Espions - Henri-Georges Clouzot

A psychiatrist, desperate for money to keep his faltering practice running, makes a deal with a spy to hide a mysterious person in his clinic in return for a million francs. As soon as the deal is struck his place is overrun by spies from both East and West, all in search of a renegade nuclear scientist. The psychiatrist's own sanity starts to break down as he submitted to unmitigated surveillance and deception.