In Hamburg, an aged sorcerer is searching for a replacement. Freddie, who's about 12, finds the wizard's book of spells and knows enough to read a few lines to his friend Emma. She repeats the lines adding exasperation about Mickey, a boy who's often mean to her. The next morning, Mickey finds himself in Emma's body, and Emma finds herself in Mickey's body. The wizard tracks down the book, takes it back, and disappears, leaving Freddy with no way to reverse the spell, which becomes permanent in 54 hours. Freddy, Emma, and Mickey must work together to search out a solution, while making discoveries about sex roles, courage, friendship, and each other
Mike Sullivan works as a hit man for crime boss John Rooney. Sullivan views Rooney as a father figure, however after his son is witness to a killing, Mike Sullivan finds himself on the run in attempt to save the life of his son and at the same time looking for revenge on those who wronged him.
When a virus leaks from a top-secret facility, turning all resident researchers into ravenous zombies and their lab animals into mutated hounds from hell, the government sends in an elite military task force to contain the outbreak.
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 MIB's untarnished mission statement – protecting Earth from the scum of the universe.