Well the premise was this guy named Willard loved rats - he had lots of them as friends and pets. He had one favorite who was all white (the good rat) - cannot remember his name and then a second black one (the bad one) appeared. Willard's second favorite named Ben.
Willard was anti-social but loved his pet rats - when people ticked him off - the rats (led by Ben) killed them. One time Willard brought his favorite rats - Ben and White guy - into the office. The boss saw the white rat and killed him so of course Ben led the crusade and the rats killed the boss. Willard was so upset upon going home he decided to kill the rats by mixing rat poison in their food. Ben being so smart "read" the poison and then the rats killed Willard.
Thus the Ben movie.