Protecting the earth from the scum of the universe.
When a government agency receives knowledge of extraterrestrial life in 1961, the secret "Men in Black" agency is created that polices aliens and protects Earth from intergalactic threats. However, when a recent recruit and his seasoned partner get wind of an intergalactic terrorist plot, they must move everything in the universe to stop it.
Five years after the retirement of Agent K and the defeat of Edgar the Bug from ''Men in Black'', the secret New York City-based agency that monitors and regulates extraterrestrial life residing on Earth, Agent J–K's former partner and hand-picked replacement–is called to investigate the murder of an alien, Ben, at his pizzeria. The waitress, Laura Vasquez, tells him that the murderers are Serleena, a shapeshifting, plant-like Kylothian who has taken the form of a lingerie model, and her two-headed servant Scrad. Laura says they were looking for something called the Light of Zartha. J is strongly attracted to Laura, and in violation of MiB rules, does not Neuralyzer her to erase her memories.
In 2012, an alien criminal named Boris the Animal, a Boglodite, escapes from a maximum-security prison on the Moon of Earth and arrives on Earth, bent on taking revenge on Agent K, who shot off his left arm and captured him in 1969. He confronts K, who is with his partner Agent J, and tells him he is "already dead". Back at MiB Headquarters, J peruses MiB's files and discovers K was responsible not only for capturing Boris, but for deploying the "ArcNet", a shield that prevented the Boglodites from conquering Earth, causing their extinction.
A London-based team of Men in Black (MIB) secret agents become involved in a series of alien attacks that sends the pair traveling around the globe in hot pursuit.