Eyes Wide Shut (1999)

Plot: Dr. Bill and Mrs. Alice Harford are a young, upper middle class couple living in a lavish apartment along Central Park West with their seven year old daughter, Helena Harford. It's the Christmas season, and like they have been the past several years, they are invited to the annual lavish Christmas ball hosted by Victor Ziegler, one of Bill's wealthy patients. Based on their individual encounters at the party, which includes Bill secretly providing his professional services to a guest, Bill and Alice have a frank discussion, largely initiated by Alice, about their sex life, their sexual fantasies - most specifically if those fantasies include other people - and fidelity. As a result, Bill begins to notice those sexual opportunities available to him outside of their marriage. Although he contemplates seizing upon some of those opportunities, it's the one mentioned to him by Nick Nightingale - a former medical school colleague who dropped out to become a full time musician, and who was the pianist at Victor's party, where he and Nick were reacquainted - that piques Bill's interest the most. Bill's interest is probably increased by Nick's pleas for him not to follow-up on what he tells him. That opportunity is a secret, by invitation only party, the latest in a series, where Nick is hired to play blindfolded, with the party location divulged to him only one hour prior to his arrival. It was during a previous party that Nick saw beneath his blindfold that it was a sex party, all the participants dressed in costume and wearing masks, probably to provide anonymity to all the attendees. Bill is able to sneak his way into this latest party, which is even more elaborate than his wildest fantasies. But what happens at the party may irreparably affect his marriage, his sex life with Alice, and their lives in their entirety.