Le Grain de sable (1964)
Directed by Pierre Kast

Film Synopsis

Coppolos, an important investment magnate, is killed when his private jet explodes.  There is no doubt that a bomb was the cause of the explosion and a criminal investigation is soon under way.  Laurent, a promising functionary at the ministry of foreign affairs, informs the inspector in charge of the case of conflicting interests for East and West.  On the East side there is Alain Compton, a young financial genius; the West is represented by Georges Richter, Coppolos' main business partner.  Then there is Anna Maria di Scorza, the authorized agent of the group, former mistress of Coppolos and Richter's ex-wife, who is now attempting to seduce Compton.  These three are competing for the whole of the dead man's vast personal fortune.  Richter conceives a devilish plan to eliminate his rivals: kill Compton and fabricate proof that will incriminate Anna Maria, whom he will then dispose of, making her death appear to be suicide.  Unfortunately, Richter is blissfully unaware that Compton has come up with exactly the same plan, with him as the first murder victim...