The story involves a 60th birthday party at which all of a family's corrupt and painful secrets are revealed at last. To the family's country inn in Denmark come the surviving children of Helge and his wife, Elsa. We meet the eldest son, Christian, his younger brother Michael, and their sister Helene. Christian's twin sister has recently committed suicide. Also gathering around the table for the patriarch's birthday are assorted spouses, relations and friends. Thomas Vinterberg's "The Celebration" mixes farce and tragedy so completely that it challenges us to respond at all. There are moments when a small, choked laugh begins in the audience and is then instantly stifled, as we realize a scene is not intended to be funny. Or is it?