In this episode, Bob's brother Cecil gets him out of prison and Bob starts working for Cecil. But Bart thinks Bob is still evil and tries to prove it. He finds a plot to destroy the Springfield Dam, and thinks it is Bob's idea. But later they learn it was Cecil. They try to thwart his plan, and in the end, Cecil is arrested, and so is Bob, even though he didn't do anything.
A great episode, as I have stated, Bob episodes are generally great. One of my favorites from season 8, my overall grade is easily an A+