A secret government organization made up of men provide intergalactic immigration services for Earth-bound aliens.
When Kay is infected with Millicrons, Jay takes his place on an assignment to transport a symbiote named Troy to New York City. He has to do it within twenty hours or be permanently absorbed by Troy. But Buzzard returns and is looking to capture the symbiote for his mysterious boss.
An Inanimate, a shapeshifter capable of disgusing itself as inanimate objects, escapes from prison to Earth. But the MIB get some help from Eileen, an intergalactic cop that stirs up some old feelings for Kay.
An insane Alcidian named Forbus is hunting humans, draining them of their bodily fluids. But during the pursuit, Forbus forms a psychic link with Kay, making him feel whatever he feels.
Jay mistakes a Cerebro-Accelerator for a pair of head phones, making him the smartest man on Earth. However, this will also cause his brain to explode in twenty-two hours. But his advanced brain is MIB's only hope when someone uses time travel to erase the five founders of MIB from existence.
Alien dream eaters known as the Vermax attack the crew of a returning NASA space shuttle. When Jay, Kay and Elle arrive at the landing sight, a Vermax attaches itself to Jay and sends him into a deep sleep. Elle enters Jay's dreams to get him to wake up and remove the Vermax.
The Blastula are increasing the temperature on Earth in their plot to colonize the planet.
