Justine (Kirsten Dunst) and Michael (Alexander Skarsgard) are celebrating their marriage at a sumptuous party in the home of her sister Claire (Charlotte Gainsbourg), and brother-in-law John (Kiefer Sutherland). Despite Claire's best efforts, the wedding is a fiasco, with family tensions mounting and relationships fraying. And as Claire tries to maintain the party's celebratory spirit, Justine struggles against her own dark demons. Meanwhile, a planet called Melancholia is heading directly towards Earth.