When Thomas Archer's happy and successful life is all but ruined following a horrific attack he is presented with a perfect opportunity to exact physical revenge upon the man who caused all his grief. However the immediate consequences of his actions and in-actions are much more complicated than he imagined.

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. It's been four years since the alien-seeking agents averted an intergalactic disaster of epic proportions. Now it's a race against the clock as Jay must convince Kay – who not only has absolutely no memory of his time spent with the MIB, but is also the only living person left with the expertise to save the galaxy – to reunite with the MIB before the earth submits to ultimate destruction.