One Piece has returned! This is a good chapter, with Mr. 3 joining Luffy's idiot brigade (his intention the same as Buggy's--distraction for his own escape!), Buggy reacting to Gear Three, meeting the chief warden of Impel Down, Hancock pretending to be innocent, and meeting the last Shichibukai... himself a prisoner!
Now... what could have been the reason for the last guys imprisonment? If I had to guess, I'd say he tried to enforce the World Government's own laws against them, much to their displeasure.