Men In Black 3 or MIB-3 opens with a woman (Nicole Schrezinger) walking into a high-security prison, carrying a cake intended for a dangerous prisoner, Boris the Beast (Jemaine Clement). However, hidden inside this cake is a tarantula-like alien, which cuts off Boris's shackes and frees him. Boris then escapes by gaining control of a huge gun and blowing apart a hole in the wall, through which the guards are sucked out. We later find that the prison is located on the moon.
Boris comes to earth with one mission: to go back in time to 1969 and kill Agent K (Tommy Lee Jones), who had cut off his hand and imprisoned him in 1969, and had deployed a protective shield around the earth which protects humanity from alien attacks. K's partner J (Will Smith) suddenly finds himself in an alternate reality where K had died in 1969 trying to arrest Boris, nobody in the MIB agency has known K except O (the new head of the agency, Emma Thompson), and the protective shield does not exist anymore. Boris's species, the Bogladites, are all around the earth, preparing for an invasion. To set things right in the past, J has to travel back in time, save K and make sure the shield is deployed.
J goes back to July 16, 1969 and meets up with a young Agent K (Josh Brolin) who is much friendlier than the older K. Though he does not fully trust J, they both get along well, and K believes J's story that he's from the future and his reason for being there. They meet an alien, Griffin, who has the power to view several alternate dimensions simultaneously and thus predict the future. He hands over the shield to K and tells him to attach it to the top of Apollo 11, the first manned mission to the moon, which is due to be launched in a few hours. Boris finds his way there and kidnaps Griffin, but he is saved by the two agents.
J, K and Griffin make their way to Cape Canaveral using jet-packs just a few minutes before the launch. They are stopped by the security but Griffin makes the security head, a colonel, witness the future and the importance of the mission, who then escorts the three of them to the rocket's top. Here, Boris from 1969 as well as the Boris who travelled back from the present, attack them, but after a long fight both of them are defeated, and the shield is attached to the top of the rocket which gets deployed when the rocket exits the atmosphere.
However, the 1969's Boris is still alive, and tries to kill K, but the colonel saves K's life but ends up being killed by Boris, who is later killed by K. Meanwhile the colonel's son walks up to K, who is none other than a young James, who went on to become Agent J. The older agent J watches from a distance, having just watched his father die a heroic death, about which he had been unaware of so far. K walks along with young James along the beach, and it is implied that he took care of the child and took him under his wing all along.
Lowell Cunningham, David Koepp
Will Smith, Tommy Lee Jones and Josh Brolin
Source : baliweekly.com