A secret government organization made up of men provide intergalactic immigration services for Earth-bound aliens.
While trying to get Skraaldians out of New York sewers, Jay uses his Noisy Cricket on one and kills it. Problem is, all Skraaldians are psychically linked and know what Jay did. And every last one will go after him to settle the score.
Jay and Kay investigate a crashed alien ship in the woods when they encounter Treblor, an alien cop from the Zombarian Retrieval Department. Treblor says the owner of the crashed ship is a fugitive named Z-Ron. While Jay goes out ahead to get Z-Ron, Kay learns Treblor isn't who he says he is.
A Charnok has to come to Earth and ransacked Jeebs' pawn shop as well as hunting reliable MIB informant, Frank the Pug. After some investigating, Jay and Kay learn the Charnok was trying to buy a Void Density Core from Jeebs, who didn't want to sell it. Frank made off with it during the fight and accidentally swallowed it. Now the MIB have to get the VDC out of him before it detonates and sucks the city into a miniature black hole.
Investigating the theft of a Sintillian heart, Kay learns the culprit is Alpha, his former mentor and the man who left him for dead years ago. But Jay and Kay discover Alpha now has multiple body parts grafted onto his body, becoming even more dangerous.
Jay goes undercover as a Tarkan bodyguard at an alien conference to protect Dirndl, Trade Minister of Tarka, from an alien assassin.
While trying to stop alien thieves known as Chop Shoppers, Jay's accidental use of the Neuralizer erases Kay's memories and makes him think he is sixteen.