The film tells the story of the former FBI Associate Director’s efforts to leak information during Watergate.
A host of models toasted Missoni’s Award of Courage at the glitzy gala, which featured a performance by Andrea Bocelli.
The makeup artist had the house built for her around 15 years ago and is now looking to downsize.
The fashion designer has chopped the price again and is also offering it minus staff quarters.
With a new documentary and a series about the effects of the Mafia drug trade on children in Italy, Beatrice Borromeo Casiraghi hopes her work will lead to action of some kind.
Designers and personalities including Haider Ackermann, Clémence Poésy and Charlotte Casiraghi attended the event.
The fashion designer owned it for eight years, before selling for $7.9 million in 2012.
The socialite and her billionaire husband had originally sought $7.25 million for the Flatiron spread.