Kay and Jay reunite to provide our best, last and only line of defense against a sinister seductress who levels the toughest challenge yet to the MIBs untarnished mission statement: protecting the earth from the scum of the universe. It's been four years since the alien-seeking agents averted an intergalactic disaster of epic proportions. Kay has since returned to the comforts of civilian life, while Jay continues to work for the Men In Black, the highly funded yet unofficial government agency that regulates all things alien on earth. While investigating a seemingly routine crime, Jay uncovers a diabolical plot masterminded by Serleena, an evil Kylothian monster who disguises herself as a sexy lingerie model. When Serleena takes the entire MIB building hostage, there is only one person left Jay can turn to -- his former MIB partner, who is now a drone in another large government office, the U.S. postal service, and prefers simple pleasures like his wife's cookies over standoffs with mammoth alien insects. It's a race against the clock as Jay must convince Kay -- who not only has absolutely no memory of his time spent with the Men In Black but also is the only living person left with the expertise to save the galaxy -- to reunite with the MIB before the earth submits to ultimate destruction.