Two sisters find their already strained relationship challenged as a mysterious new planet threatens to collide with Earth.

On the night of her wedding, Justine is struggling to be happy even though it should be the happiest day of her life. It was an extravagant wedding paid for by her sister and brother-in-law who are trying to keep the bride and all the guests in line. Meanwhile, Melancholia, a blue planet, is hurtling towards the Earth. Claire, Justine's sister, is struggling to maintain composure with fear of the impending disaster.