Four years after agents J and K averted an intergalactic disaster, J is still working for the MIB while K has returned to the comforts of civilian life. While investigating a seemingly routine crime, J uncovers a diabolical plot masterminded by Serleena, an evil Kylothian monster who disguises herself as a sexy lingerie model. It's a race against the clock as J must find and convince K--who not only has no memory of his time spent with the agency, but is also the only person alive who has the expertise to save the galaxy--to reunite with the MIB before Earth is destroyed completely.