 On a mission to where the space ship Horizon send a radio distress signal which took a century traveling, the Enterprise reaches a planet where beaming down they find most men carry firearms, as the entire culture has been based on a book left behind from earth on Chicago Gangs in the 1920s, clearly in breech of the Federation s non-interference rule- should they make up for it? The rival gang leaders hope to enlist their superior weapons and knowledge to achieve planetary domination. Kirk and Spock find themselves forced to play mob bosses too...