Monica Vitti in Modesty Blaise (1966)

Modesty Blaise (Monica Vitti), a secret agent whose hair color, hair style, and mod clothing change at a snap of her fingers, is being used by the British government as a decoy in an effort to thwart a diamond heist. She is being set-up by the feds, but is wise to the plot, and calls in sidekick Willie Garvin (Terence Stamp) and a few other friends to outsmart them. Meanwhile, at his island hideaway, Gabriel (Sir Dirk Bogarde), the diamond thief, has his own plans for Blaise and Garvin.