Agent J must travel back in time to MIB's early years in the 1960s and save his partner, Agent K, from being assassinated by an alien. Along the way, Agent J teams up with young Agent K and learns that there are secrets to the universe that Agent K never told him.

Two agents who keep an eye on aliens in New York City must try to save the world after the aliens threaten to blow it up; Agent Jay must call Agent Kay out of retirement in order to help rid the earth of a Kylothian monster who is threatening humanity; agent Jay must travel back in time to 1969 to save his partner, Agent Kay, from being assassinated by an alien.

New York City is being threatened by a villainous bug who has inhabited the body of a farmer. The mission is to locate and exterminate the bug before it destroys the planet.

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,...