Mercury is a story of five friends. A factory named Corporate Earth is shut down by the government because of poisoning. Every year at ‘Hope School for the Differently Abled’, a Memorial Day is held to pay respect to the 84 lives lost due to mercury poisoning from the town’s defunct thermometer factory. A generation of survivors, maimed by the poisoning, gather to commemorate the dead. That night five friends have a party and Micheal, Meera and their three friends climb down the cliff top to the Corporate Earth and throws rocks on it. They hit a man (Prabhu Deva) and they bury him somewhere near Corporate Earth. One of them lost his iPod and next day returns in search for it. The man gets up and kidnaps Meera and keeps in the closed Corporate Factory and the four friends go inside and one by one gets killed. Meera gets to know he has mercury poisoning related disorder. Corporate Earth factory is burnt in the end and prabhu deva dies.