The Tall Blond Man with One Black Shoe (1972)

Two factions of the French Secret Service involve a seemingly normal orchestra player, Francois Perrin, into their battle as one side uses him as a decoy. Soon, agents are all over the place, and one of them, Christine, is sent to seduce Francois. Meanwhile, Francois has his own problems, tangled up in an affair with his best friend's wife.